El Niño live tracker

1. On NOAA’s official three-month measure, the relative index (RONI) reads 2.0 for August–October 2026, 0.4 below its record of 2.4 (December 1982–February 1983); the traditional ONI is 2.5 °C above normal, 0.1 °C below its record of 2.6 °C (November 2015–January 2016), provisionally the highest August–October since 1950. Both are provisional: NOAA may revise them for up to two months. (FloodRadar’s reading of NOAA CPC’s RONI.ascii.txt and oni.ascii.txt, both since 1950.)
2. In the week of 25–31 October 2026 Niño 3.4 was 3.4 °C above normal, which equals the weekly record of 3.4 °C (week of 18–24 October 2026); on the relative scale it reads 2.5, 0.4 below the record of 2.9 (week of 26 December 1982–1 January 1983). (FloodRadar’s reading of NOAA CPC’s wksst9120.for and rel_wksst9120.txt, both since 1981.)
3. During this event Niño 1+2 has already had its highest week since September 1981 on the traditional scale, but not on the relative scale. (FloodRadar’s reading of NOAA CPC’s wksst9120.for and rel_wksst9120.txt, both since 1981.)
4. During this event Niño 3 has had its highest week since September 1981 on both scales. (FloodRadar’s reading of NOAA CPC’s wksst9120.for and rel_wksst9120.txt, both since 1981.)

Each Niño region’s latest week, the week of 25–31 October 2026, against its highest week, on both scales. Traditional: FloodRadar’s reading of NOAA CPC’s wksst9120.for, since 1981. Relative: FloodRadar’s reading of NOAA CPC’s rel_wksst9120.txt, since 1981. Swipe the table sideways for the relative scale.

Niño 3.4 over a month, three months and a day, against the highest on each file. The three-month row puts NOAA’s traditional ONI beside its official relative RONI. Swipe the table sideways for the relative scale.

NOAA’s table rounds these to one decimal (ONI 2.46 as 2.5 and RONI 1.97 as 2.0); the file carries two. The latest seasons are provisional: NOAA may revise them for up to two months.

Records raised during this event (13)

• Niño 1+2 weekly, against normal 5.4 °C week of 25–31 October 2026 Raised five times since the week of 6–12 September 2026 Before this event: 4.5 °C, week of 26 June–2 July 1983 (FloodRadar’s reading of NOAA CPC’s wksst9120.for, since 1981; against 1991–2020)
• Niño 3 weekly, against normal 4.4 °C week of 25–31 October 2026 Raised eight times since the week of 30 August–5 September 2026 Before this event: 3.3 °C, week of 9–15 November 1997 (FloodRadar’s reading of NOAA CPC’s wksst9120.for, since 1981; against 1991–2020)
• Niño 3 weekly relative index 3.7 week of 25–31 October 2026 Raised once, in the week of 25–31 October 2026 Before this event: 3.6, week of 26 December 1982–1 January 1983 (FloodRadar’s reading of NOAA CPC’s rel_wksst9120.txt, since 1981; against 1991–2020)
• Niño 3.4 weekly, against normal 3.4 °C week of 18–24 October 2026 Raised four times since the week of 20–26 September 2026 Before this event: 3.0 °C, week of 15–21 November 2015 (FloodRadar’s reading of NOAA CPC’s wksst9120.for, since 1981; against 1991–2020)
• Niño 1+2 monthly, against normal 5.25 °C October 2026 Raised three times since August 2026 Before this event: 4.03 °C, June 1983 (FloodRadar’s reading of NOAA CPC’s sstoi.indices, since 1982; against 1991–2020)
• Niño 1+2 monthly relative index 4.43 October 2026 Raised once, in October 2026 Before this event: 4.33, June 1983 (FloodRadar’s reading of NOAA CPC’s rel_mthsst9120.txt, since 1981; against 1991–2020)
• Niño 3 monthly, against normal 4.16 °C October 2026 Raised three times since August 2026 Before this event: 3.07 °C, December 1997 (FloodRadar’s reading of NOAA CPC’s sstoi.indices, since 1982; against 1991–2020)
• Niño 3 monthly relative index 3.56 October 2026 Raised once, in October 2026 Before this event: 3.22, December 1982 (FloodRadar’s reading of NOAA CPC’s rel_mthsst9120.txt, since 1981; against 1991–2020)
• Niño 3.4 monthly, against normal 3.25 °C October 2026 Raised twice since September 2026 Before this event: 2.72 °C, November 2015 (FloodRadar’s reading of NOAA CPC’s sstoi.indices, since 1982; against 1991–2020)
• Upper-ocean heat, 130°E–80°W 2.23 °C September 2026 Raised four times since April 2026 Before this event: 1.55 °C, June 1997 (FloodRadar’s reading of NOAA CPC’s heat_content_index.txt, since 1979; against 1981–2010)
• Upper-ocean heat, 160°E–80°W 2.93 °C September 2026 Raised five times since April 2026 Before this event: 2.05 °C, October 1997 (FloodRadar’s reading of NOAA CPC’s heat_content_index.txt, since 1979; against 1981–2010)
• Upper-ocean heat, 180°–100°W 3.39 °C September 2026 Raised three times since July 2026 Before this event: 2.56 °C, October 1997 (FloodRadar’s reading of NOAA CPC’s heat_content_index.txt, since 1979; against 1981–2010)
• Warm water volume, against normal 3.46 × 10¹⁴ m³ August 2026 Raised twice since July 2026 Before this event: 3.12 × 10¹⁴ m³, April 1997 (FloodRadar’s reading of NOAA PMEL’s wwv.dat, since 1980; data: GTMBA Project Office, NOAA/PMEL; against 1981–2010)

The latest 12 weeks in each Niño region

	Traditional, °C against 1991–2020				NOAA’s relative scale
	Niño 1+2	Niño 3	Niño 3.4	Niño 4	Niño 1+2	Niño 3	Niño 3.4	Niño 4
Week of 25–31 October 2026	+5.4	+4.4	+3.4	+1.4	+4.6	+3.7	+2.5	+0.2
Week of 18–24 October 2026	+5.2	+4.3	+3.4	+1.1	+4.4	+3.6	+2.5	0.0
Week of 11–17 October 2026	+5.2	+4.2	+3.3	+1.1	+4.4	+3.5	+2.4	0.0
Week of 4–10 October 2026	+5.3	+4.1	+3.2	+1.3	+4.4	+3.4	+2.4	+0.2
Week of 27 September–3 October 2026	+5.3	+4.1	+3.2	+1.3	+4.5	+3.3	+2.3	+0.1
Week of 20–26 September 2026	+4.9	+4.0	+3.1	+1.1	+3.9	+3.1	+2.2	+0.1
Week of 13–19 September 2026	+4.7	+3.8	+3.0	+1.0	+3.9	+3.0	+2.1	0.0
Week of 6–12 September 2026	+4.6	+3.7	+2.8	+0.8	+3.8	+2.9	+1.9	−0.2
Week of 30 August–5 September 2026	+4.4	+3.5	+2.8	+1.0	+3.7	+2.7	+1.9	+0.1
Week of 23–29 August 2026	+4.2	+3.3	+2.6	+0.9	+3.5	+2.6	+1.8	+0.1
Week of 16–22 August 2026	+4.0	+3.2	+2.6	+0.8	+3.2	+2.5	+1.8	0.0
Week of 9–15 August 2026	+4.1	+3.2	+2.6	+1.0	+3.4	+2.5	+1.8	+0.1

NOAA Climate Prediction Center: weekly OISST v2.1 files wksst9120.for and rel_wksst9120.txt, against 1991–2020.

NOAA’s outlook of 8 October 2026 puts the peak of its median forecast in October–December 2026, at 2.74 on its relative three-month index (nine-in-ten range 2.25 to 3.23). The record on that index is 2.40, for December 1982–February 1983 (FloodRadar’s reading of NOAA CPC’s RONI.ascii.txt, since 1950); the latest observed value is 2.0, for August–October 2026 (provisional). NOAA puts the chance that El Niño is still in place in February–April 2027 at 98%, and in April–June 2027 at 45%.

NOAA’s strength odds of 8 October 2026 put the chance that its relative three-month index sits at 2.0 or above at 100% in September–November 2026, its largest of the nine seasons in the table, and at 0% by May–July 2027. (NOAA Climate Prediction Center.)

Forecast issued 8 October 2026, in per cent, on NOAA’s relative three-month index

	El Niño, all strengths	El Niño side, by strength				Neutral−0.5 to 0.5	La Niña side, by strength
		2.0 or above	1.5 to 2.0	1.0 to 1.5	0.5 to 1.0		−1.0 to −0.5	−1.5 to −1.0	−2.0 to −1.5	−2.0 or below
September–November 2026	100	100	0	0	0	0	0	0	0	0
October–December 2026	100	100	0	0	0	0	0	0	0	0
November 2026–January 2027	100	96	4	0	0	0	0	0	0	0
December 2026–February 2027	100	81	16	3	0	0	0	0	0	0
January–March 2027	100	46	37	15	2	0	0	0	0	0
February–April 2027	98	6	32	44	16	2	0	0	0	0
March–May 2027	85	0	5	32	48	15	0	0	0	0
April–June 2027	45	0	0	7	38	54	1	0	0	0
May–July 2027	17	0	0	2	15	70	12	1	0	0

NOAA Climate Prediction Center: RONI strength probabilities, issued 8 October 2026. NOAA rounds to whole per cents.

Observed: NOAA’s relative three-month index (RONI)

Season	RONI
March–May 2026	−0.04
April–June 2026	+0.49
May–July 2026	+0.97
June–August 2026	+1.36
July–September 2026	+1.69 provisional
August–October 2026	+1.97 provisional

Forecast issued 8 October 2026: NOAA’s range for its relative three-month index, by percentile

Season	5th	15th	25th	Middle (50th)	75th	85th	95th
September–November 2026	2.18	2.29	2.35	2.47	2.59	2.65	2.76
October–December 2026	2.25	2.43	2.54	2.74	2.94	3.05	3.23
November 2026–January 2027	2.00	2.24	2.39	2.65	2.92	3.06	3.31
December 2026–February 2027	1.58	1.87	2.04	2.36	2.68	2.85	3.14
January–March 2027	1.13	1.42	1.59	1.90	2.22	2.39	2.67
February–April 2027	0.66	0.91	1.05	1.33	1.60	1.75	2.00
March–May 2027	0.23	0.45	0.58	0.83	1.08	1.21	1.43
April–June 2027	−0.22	0.01	0.14	0.40	0.66	0.79	1.02
May–July 2027	−0.68	−0.41	−0.26	0.03	0.32	0.48	0.74

NOAA Climate Prediction Center: RONI.ascii.txt and the RONI forecast ranges issued 8 October 2026. Values as NOAA publishes them, shown to two decimals. The record line is FloodRadar’s reading of NOAA CPC’s RONI.ascii.txt, since 1950.

Forecast October 2026: IRI’s model averages for the Niño 3.4 three-month average, about, °C against normal

Season	All models	Physics-based	Statistics-based	Lowest	Highest	Models
October–December 2026	3.5	3.6	3.2	2.5	4.3	27
November 2026–January 2027	3.5	3.7	3.3	2.4	4.2	27
December 2026–February 2027	3.3	3.4	3.1	2.4	4.2	27
January–March 2027	2.8	2.9	2.7	2.0	4.0	27
February–April 2027	2.2	2.2	2.2	1.2	3.2	23
March–May 2027	1.6	1.7	1.6	0.7	2.7	21
April–June 2027	1.1	1.4	0.9	0.3	2.1	20
May–July 2027	0.7	1.0	0.4	−0.2	1.6	18
June–August 2027	0.3	0.7	0.0	−0.9	1.8	18

CC BY 4.0. ENSO Forecast Data © 2002-2026 by International Research Institute for Climate and Society is licensed under Creative Commons Attribution 4.0 International. Values read from the published figure; redrawn by FloodRadar.

NOAA’s range is on its relative index and IRI’s models are on the traditional index, so the two forecasts cannot be read against each other.

The highest three-month value of NOAA’s relative index since 1950 is 2.40, for December 1982–February 1983 (FloodRadar’s reading of NOAA CPC’s RONI.ascii.txt, since 1950). Every value above that line is outside experience.

The highest three-month average of NOAA’s monthly Niño 3.4 file since 1982 is 2.87, for August–October 2026 (FloodRadar’s reading of NOAA CPC’s sstoi.indices, three-month means, since 1982). Every value above that line is outside experience.

NOAA says the strength of an event “does not necessarily correspond with the strength of the influence or expected impact” (NOAA Climate Prediction Center).

Past El Niño winters in FloodRadar’s archive

In FloodRadar’s archive of Environment Agency flood alerts and warnings raised in England each October to March since 2006–07, the seven El Niño winters (classed by NOAA’s traditional ONI) ranged from 1,479 (2018–19) to 8,291 (2023–24), an average of 4,116; the four neutral winters averaged 4,173 and the nine La Niña winters averaged 2,739. That is context, not a forecast. Classed by NOAA’s official relative index instead, 2019–20 is not an El Niño winter, and the El Niño average is 3,569 against 5,966 for the three neutral winters.

• El Niño winters (7) 1,479 (2018–19) to 8,291 (2023–24), average 4,116
• Neutral winters (4) 1,714 (2016–17) to 5,886 (2013–14), average 4,173
• La Niña winters (9) 723 (2011–12) to 5,316 (2025–26), average 2,739
• 09,000

FloodRadar’s archive of Environment Agency flood alerts, warnings and severe warnings in England, October to March; winters classed by NOAA’s November–January ONI from oni.ascii.txt (0.5 or more El Niño, −0.5 or less La Niña). The bar runs from the quietest to the busiest winter of each kind; the mark is the average.

Britain right now

These show what is happening in Britain now. They are not a measure of El Niño’s effect. No single wet week can be pinned on it.

The Met Office is explicit that El Niño “does not determine exactly what conditions we will experience”.

• What to expect in the UK, and when
• Your river in past El Niño winters

Niño 3.4 read four ways: over a day, a week, a month and three months, on the traditional scale and on NOAA’s relative scale

	How much warmer the water is (traditional)	How much El Niño stands out (NOAA’s official relative scale)
Latest day1 November 2026	3.4°Cpreliminary	Not published on the relative index
	FloodRadar calculation: Climate Reanalyzer’s NOAA OISST v2.1 daily Niño 3.4 temperature minus its 1991–2020 daily mean, shown to one decimal; the latest days are preliminary and NOAA replaces them after about two weeks.
Latest weekweek of 25–31 October 2026	3.4°C	2.5
Latest monthOctober 2026	3.25°C	2.47
Latest three monthsAugust–October 2026	ONI2.5°Cprovisional	RONI2.0provisional
	NOAA’s table rounds these to one decimal (ONI 2.46 as 2.5 and RONI 1.97 as 2.0); the file carries two. The latest seasons are provisional: NOAA may revise them for up to two months.

NOAA’s relative scale reads 0.9 lower than the traditional index in the week of 25–31 October 2026 (weekly Niño 3.4).

Is climate change involved?

ONI minus RONI, averaged over each decade (index units)

Decade	ONI minus RONI	Seasons
1990s	−0.11	120
2000s	+0.01	120
2010s	+0.22	120
2020s so far	+0.44	81

FloodRadar calculation from NOAA Climate Prediction Center’s oni.ascii.txt and RONI.ascii.txt, same seasons only.

The same month in each event, °C against 1981–2010

Month	°C
October 1982	+2.07
October 1997	+2.56
October 2015	+1.91
October 2026	+3.36

The latest 12 months, °C against 1981–2010, by the span of longitude averaged

Month	130°E–80°W	160°E–80°W	180°–100°W
October 2026	+2.15	+2.93	+3.36
September 2026	+2.23	+2.93	+3.39
August 2026	+2.19	+2.77	+3.23
July 2026	+2.03	+2.50	+2.96
June 2026	+1.79	+2.14	+2.26
May 2026	+1.67	+1.97	+1.99
April 2026	+1.85	+2.07	+2.24
March 2026	+1.38	+1.39	+1.36
February 2026	+1.08	+1.02	+1.15
January 2026	+0.64	+0.45	+0.49
December 2025	+0.26	+0.01	−0.03
November 2025	−0.02	−0.33	−0.46

NOAA Climate Prediction Center: heat_content_index.txt, against 1981–2010.

The warm water volume of the equatorial Pacific was 3.16 × 10¹⁴ cubic metres above its 1981–2010 average in September 2026, down from this event’s high of 3.46 × 10¹⁴ cubic metres (August 2026), which is the monthly record. (FloodRadar’s reading of NOAA PMEL’s wwv.dat, since 1980; data: GTMBA Project Office, NOAA/PMEL.)

Is the atmosphere playing along?

• Pressure see-saw (SOI)

  Tilted the El Niño way (−1.1, October 2026)

  NOAA CPC’s standardised index, against 1981–2010. The verdict is FloodRadar’s reading, not NOAA’s.

  How this is judged: Pressure see-saw (SOI)

  FloodRadar’s reading, not NOAA’s: less than half a standard deviation from normal is near normal; half a standard deviation or more below normal tilts the El Niño way, half or more above it the La Niña way. Each tile is judged against its own file’s normal (1981–2010).

• Trade winds

  Tilted the El Niño way (−3.4, October 2026)

  NOAA CPC’s standardised index, against 1981–2010. The verdict is FloodRadar’s reading, not NOAA’s.

  How this is judged: Trade winds

  FloodRadar’s reading, not NOAA’s: less than half a standard deviation from normal is near normal; half a standard deviation or more below normal tilts the El Niño way, half or more above it the La Niña way. Each tile is judged against its own file’s normal (1981–2010).

• Cloud over the central Pacific

  Tilted the El Niño way (−43.54 W/m², −2.9 standard deviations, October 2026)

  FloodRadar standardisation: the month’s anomaly (against 1991–2020) divided by the 1991–2020 spread of monthly anomalies in NOAA CPC’s file. The verdict is FloodRadar’s reading, not NOAA’s.

  How this is judged: Cloud over the central Pacific

  FloodRadar’s reading, not NOAA’s: less than half a standard deviation from normal is near normal; half a standard deviation or more below normal tilts the El Niño way, half or more above it the La Niña way. Each tile is judged against its own file’s normal (1991–2020).

El Niño moves ocean heat into the air, so global temperature usually peaks a few months after the Pacific does. That is why forecasters expect 2027, not 2026, to set the annual record (Met Office, 21 August 2026).

Of the 305 days of 2026 with final data, 68 were the warmest on record for their date in the ERA5 global air-temperature record, which begins in 1940; the latest day, 2 November 2026, was 1.11 °C above the 1991–2020 average, provisionally above the record for its date — confirmed when final data arrives. (FloodRadar’s reading of Copernicus’s era5_daily_series_2t_global.csv, since 1940; Copernicus Climate Change Service / ECMWF, ERA5.)

of the 305 days of 2026 with final data were the warmest on record for their date

68

of the 305 days of 2026 with final data were the warmest on record for their date

Global air, ERA5, since 1940

days in a row, up to the latest final day, the sea surface has been the warmest on record for its date

139

days in a row, up to the latest final day, the sea surface has been the warmest on record for its date

Sea surface 60°S–60°N, ERA5, since 1979 — FloodRadar’s reading

months since 1940 at or above 1.5 °C over 1850–1900

31

months since 1940 at or above 1.5 °C over 1850–1900

FloodRadar estimate from ERA5 and C3S’s monthly offsets

Copernicus Climate Change Service / ECMWF, ERA5 daily series (era5_daily_series_2t_global.csv and era5_daily_series_sst_60S-60N_ocean.csv). CC BY 4.0. Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.

October 2026 was an estimated 1.75 °C above the 1850–1900 level (FloodRadar estimate from ERA5 daily data and C3S’s offset for the month), one of 31 months since 1940 at or above 1.5 °C on this estimate (three months lie within 0.01 °C of the line, where C3S’s own monthly figure can fall either side). Single months above 1.5 °C are not a breach of the Paris limit, which refers to a roughly 20-year average.

The latest 12 months: global air temperature above 1850–1900 (FloodRadar estimate)

Month	°C above 1850–1900	Days
October 2026	1.75	31
September 2026	1.63	30
August 2026	1.65	31
July 2026	1.47	31
June 2026	1.39	30
May 2026	1.42	31
April 2026	1.43	30
March 2026	1.48	31
February 2026	1.50† — within 0.01 °C of the 1.5 °C line, and below it on the unrounded estimate	28
January 2026	1.47	31
December 2025	1.42	31
November 2025	1.54	30

† Within 0.01 °C of the 1.5 °C line on the unrounded estimate, so this month can print as 1.50 and still sit below it — and C3S’s own monthly figure can fall either side. The count above is judged unrounded, not on the two decimals shown here.

FloodRadar estimate: the mean of ERA5 daily anomalies against 1991–2020 plus C3S’s pre-industrial offset for that calendar month.

°C against 1991–2020, ECMWF’s scale, ends open beyond ±12. The colour steps run from dark blue, 12 °C or more colder than normal, through pale colours near normal, to dark red, 12 °C or more warmer.

Map: Copernicus Climate Change Service / ECMWF, ERA5 via Climate Pulse, redrawn at half size; coastlines drawn by FloodRadar. CC BY 4.0. Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.

1. Week of 25–31 October 2026

   • Niño 3.4 held at 3.4 °C above normal.
   • Niño 3 raised its own record to 4.4 °C above normal (FloodRadar’s reading of NOAA CPC’s wksst9120.for, since 1981).
   • Niño 1+2 raised its own record to 5.4 °C above normal (FloodRadar’s reading of NOAA CPC’s wksst9120.for, since 1981).
   • On NOAA’s relative scale, Niño 3 set a new record: it reads 3.7, the highest week since September 1981 (FloodRadar’s reading of NOAA CPC’s rel_wksst9120.txt, since 1981).
   • IRI published its October 2026 collection of model forecasts.
   • NOAA revised weekly Niño 1+2 for the week of 4–10 October 2026 from 5.2 to 5.3.
   • NOAA revised monthly relative Niño 1+2 for September 2026 from 3.9 to 4.0.
   • NOAA revised weekly Niño 3 for the week of 27 September–3 October 2026 from 4.0 to 4.1.
   • NOAA revised weekly Niño 3.4 for the week of 4–10 October 2026 from 3.3 to 3.2.
   • NOAA revised weekly Niño 4 for the week of 27 September–3 October 2026 from 1.2 to 1.3.
   • NOAA revised weekly relative Niño 4 for the week of 11–17 October 2026 from −0.1 to 0.0.

2. Week of 18–24 October 2026

   • Niño 3.4 rose 0.1 °C to 3.4 °C above normal, its highest of this event.
   • Niño 3.4 raised its own record to 3.4 °C above normal (FloodRadar’s reading of NOAA CPC’s wksst9120.for, since 1981).
   • Niño 3 raised its own record to 4.3 °C above normal (FloodRadar’s reading of NOAA CPC’s wksst9120.for, since 1981).
   • NOAA revised weekly Niño 1+2 for the week of 20–26 September 2026 from 4.7 to 4.9.
   • NOAA revised weekly Niño 3 for the week of 20–26 September 2026 from 3.9 to 4.0.

3. Week of 11–17 October 2026

   • Niño 3.4 rose 0.1 °C to 3.3 °C above normal, its highest of this event.
   • Niño 3.4 raised its own record to 3.3 °C above normal (FloodRadar’s reading of NOAA CPC’s wksst9120.for, since 1981).
   • Niño 3 raised its own record to 4.2 °C above normal (FloodRadar’s reading of NOAA CPC’s wksst9120.for, since 1981).
   • NOAA revised weekly Niño 1+2 for the week of 13–19 September 2026 from 4.6 to 4.7.

4. Week of 4–10 October 2026

   • Niño 3.4 held at 3.2 °C above normal.
   • NOAA issued its October 2026 El Niño discussion on 8 October (status: El Niño Advisory), with new odds, strength and forecast-range tables.
   • NOAA revised weekly Niño 1+2 for the week of 6–12 September 2026 from 4.5 to 4.6.
   • NOAA revised weekly relative Niño 1+2 for the week of 6–12 September 2026 from 3.7 to 3.8.
   • NOAA revised weekly Niño 3.4 for the week of 6–12 September 2026 from 2.9 to 2.8.
   • NOAA revised weekly relative Niño 3.4 for the week of 6–12 September 2026 from 2.0 to 1.9.
   • NOAA revised weekly Niño 4 for the week of 6–12 September 2026 from 0.9 to 0.8.
   • NOAA revised weekly relative Niño 4 for the week of 6–12 September 2026 from −0.1 to −0.2.

5. Week of 27 September–3 October 2026

   • Niño 3.4 rose 0.1 °C to 3.2 °C above normal, its highest of this event.
   • Niño 3.4 raised its own record to 3.2 °C above normal (FloodRadar’s reading of NOAA CPC’s wksst9120.for, since 1981).
   • Niño 3 raised its own record to 4.1 °C above normal (FloodRadar’s reading of NOAA CPC’s wksst9120.for, since 1981).
   • Niño 1+2 raised its own record to 5.3 °C above normal (FloodRadar’s reading of NOAA CPC’s wksst9120.for, since 1981).
   • NOAA revised weekly Niño 1+2 for the week of 30 August–5 September 2026 from 4.6 to 4.4.
   • NOAA revised weekly relative Niño 3 for the week of 6–12 September 2026 from 2.8 to 2.9.
   • NOAA revised weekly Niño 3.4 for the week of 30 August–5 September 2026 from 2.7 to 2.8.

6. Week of 20–26 September 2026

   • Niño 3.4 rose 0.1 °C to 3.1 °C above normal, its highest of this event.
   • Niño 3.4 set a new record: 3.1 °C above normal, the highest week since September 1981 (FloodRadar’s reading of NOAA CPC’s wksst9120.for, since 1981).
   • Niño 3 raised its own record to 4.0 °C above normal (FloodRadar’s reading of NOAA CPC’s wksst9120.for, since 1981).
   • Niño 1+2 raised its own record to 4.9 °C above normal (FloodRadar’s reading of NOAA CPC’s wksst9120.for, since 1981).
   • NOAA revised weekly relative Niño 1+2 for the week of 30 August–5 September 2026 from 3.9 to 3.7.
   • NOAA revised weekly Niño 3 for the week of 23–29 August 2026 from 3.4 to 3.3.
   • NOAA revised weekly relative Niño 3.4 for the week of 30 August–5 September 2026 from 1.8 to 1.9.
   • NOAA revised weekly Niño 4 for the week of 23–29 August 2026 from 1.0 to 0.9.

7. Week of 13–19 September 2026

   • Niño 3.4 rose 0.2 °C to 3.0 °C above normal, its highest of this event.
   • Niño 3 raised its own record to 3.8 °C above normal (FloodRadar’s reading of NOAA CPC’s wksst9120.for, since 1981).
   • Niño 1+2 raised its own record to 4.7 °C above normal (FloodRadar’s reading of NOAA CPC’s wksst9120.for, since 1981).

8. Week of 6–12 September 2026

   • Niño 3.4 held at 2.8 °C above normal.
   • Niño 3 raised its own record to 3.7 °C above normal (FloodRadar’s reading of NOAA CPC’s wksst9120.for, since 1981).
   • Niño 1+2 set a new record: 4.6 °C above normal, the highest week since September 1981 (FloodRadar’s reading of NOAA CPC’s wksst9120.for, since 1981).
   • NOAA issued its September 2026 El Niño discussion on 10 September (status: El Niño Advisory), with new odds, strength and forecast-range tables.

• 21 On time
• 0 Late
• 0 Switched off
• 0 No data yet

Each source is judged on its own clock: it is late when its newest data is older than that source normally runs behind. These figures were built 4 November 2026, 06:25 UTC.

Every source this page reads, and how fresh it is

Source	State	Latest data
Weekly sea temperatures in the four Niño regions (OISST v2.1, against 1991–2020)NOAA Climate Prediction Center	On time	Latest data: 31 October 2026Next expected 9 November 2026
Weekly relative Niño indices (tropics-wide warming removed)NOAA Climate Prediction Center	On time	Latest data: 31 October 2026Next expected 9 November 2026
Oceanic Niño Index, three-month seasons (ERSST v6)NOAA Climate Prediction Center	On time	Latest data: 31 October 2026Next expected 5 December 2026
Relative Oceanic Niño Index — NOAA’s official El Niño measure since February 2026NOAA Climate Prediction Center	On time	Latest data: 31 October 2026Next expected 5 December 2026
Monthly sea temperatures in the four Niño regions (OISST v2.1)NOAA Climate Prediction Center	On time	Latest data: 31 October 2026Next expected 5 December 2026
Monthly relative Niño indicesNOAA Climate Prediction Center	On time	Latest data: 31 October 2026Next expected 5 December 2026
Southern Oscillation Index (Tahiti minus Darwin air pressure)NOAA Climate Prediction Center	On time	Latest data: 31 October 2026Next expected 5 December 2026
Central Pacific trade-wind index (850 hPa)NOAA Climate Prediction Center	On time	Latest data: 31 October 2026Next expected 5 December 2026
Central Pacific outgoing longwave radiation (cloud and rain over the dateline)NOAA Climate Prediction Center	On time	Latest data: 31 October 2026Next expected 5 December 2026
Upper-ocean heat content along the equator (top 300 m, against 1981–2010)NOAA Climate Prediction Center	On time	Latest data: 31 October 2026Next expected 5 December 2026
Warm water volume of the equatorial Pacific (water warmer than 20 °C; 5°S–5°N, 120°E–80°W; against 1981–2010)GTMBA Project Office, NOAA/PMEL	On time	Latest data: 30 September 2026Next expected 20 November 2026
Daily Niño 3.4 sea temperature (OISST v2.1)Climate Reanalyzer, University of Maine · NOAA OISST v2.1	On time	Latest data: 1 November 2026Next expected 5 November 2026
Global surface air temperature, every day since 1940 (ERA5)Copernicus Climate Change Service / ECMWF (ERA5)	On time	Latest data: 2 November 2026Next expected 5 November 2026
Sea surface temperature, 60°S–60°N, every day since 1979 (ERA5)Copernicus Climate Change Service / ECMWF (ERA5)	On time	Latest data: 2 November 2026Next expected 5 November 2026
NOAA’s monthly El Niño discussion and alert statusNOAA Climate Prediction Center	On time	Latest data: issued 8 October 2026Next expected 12 November 2026
NOAA’s odds of El Niño, neutral and La Niña for the next nine seasonsNOAA Climate Prediction Center	On time	Latest data: issued 8 October 2026Next expected 12 November 2026
NOAA’s odds for how strong the event will beNOAA Climate Prediction Center	On time	Latest data: issued 8 October 2026Next expected 12 November 2026
NOAA’s forecast range for the relative Niño 3.4 indexNOAA Climate Prediction Center	On time	Latest data: issued 8 October 2026Next expected 12 November 2026
Forecasts from IRI’s collection of computer modelsInternational Research Institute for Climate and Society, Columbia University	On time	Latest data: 31 October 2026Next expected 19 November 2026
Daily map of sea temperature against normal, quarter-degree (OISST v2.1, against 1971–2000)NOAA NCEI OISST v2.1, served by NOAA CoastWatch	On time	Latest data: 2 November 2026Next expected 4 November 2026
Daily map of air temperature against normal (ERA5)Copernicus Climate Change Service / ECMWF (ERA5)	On time	Latest data: 2 November 2026Next expected 5 November 2026

“NOAA’s official El Niño measure since February 2026” is the Climate Prediction Center’s own words: CPC adopts Relative Oceanic Niño Index (RONI) for reliable, responsive monitoring and tracking of ENSO, February 2026. The traditional ONI is still published, and this page shows both.

What each figure is measured against

Base periods

Figure	Against
Weekly and monthly Niño values, traditional and relative	1991–2020
Daily Niño 3.4 (FloodRadar calculation)	1991–2020
Oceanic Niño Index (ONI), three months	centred 30-year periods
Relative Oceanic Niño Index (RONI), three months	1991–2020, with the tropics-wide mean removed and rescaled
Upper-ocean heat	1981–2010
Warm water volume	1981–2010
Pressure see-saw (SOI)	1981–2010
Trade winds	1981–2010
Cloud over the central Pacific	1991–2020
The globe, its poster and the equator strip	1971–2000
Global air and sea-surface temperature (ERA5)	1991–2020
Global temperature against the pre-industrial level	FloodRadar estimate: the mean of ERA5 daily anomalies against 1991–2020 plus C3S’s pre-industrial offset for that calendar month.
The daily air-temperature map (Copernicus Climate Pulse)	1991–2020

No record, rank or same-scale comparison on this page mixes two of these base periods. There is one deliberate exception, and its whole subject is the difference between them: ONI minus RONI, which subtracts an index measured against 1991–2020 with the tropics taken out from one measured against moving 30-year periods.

How records are judged

Records are FloodRadar’s reading of NOAA CPC’s files, judged at the precision NOAA publishes: wksst9120.for (since September 1981) and rel_wksst9120.txt (since September 1981) for the weekly figures; sstoi.indices (since 1982) and rel_mthsst9120.txt (since 1981) for the monthly figures; oni.ascii.txt (since 1950) and RONI.ascii.txt (since 1950) for the three-month figures. The daily figure is FloodRadar’s calculation from Climate Reanalyzer’s NOAA OISST v2.1 series (since 1981). Provisional and preliminary values cannot set or lose a record.

FloodRadar’s rule: this event began with the first week of the current unbroken run of weekly Niño 3.4 readings 0.5 °C or more above normal (NOAA CPC weekly OISST v2.1, against 1991–2020). On that rule it began in the week of 12–18 April 2026.

Sources and licences

• NOAA Climate Prediction Center; NOAA NCEI OISST v2.1, served by NOAA CoastWatch

  wksst9120.for, rel_wksst9120.txt, oni.ascii.txt, RONI.ascii.txt, sstoi.indices, rel_mthsst9120.txt, soi, cpac850, cpolr.mth.91-20.ascii, heat_content_index.txt, ensodisc.txt, probabilities, strengths, outlook, ncdcOisst21NrtAgg_LonPM180.csv

  US Government work in the public domain (National Weather Service terms: free to use for any lawful purpose; no endorsement by NOAA is implied).

• GTMBA Project Office, NOAA/PMEL

  wwv.dat

  US Government work in the public domain. NOAA asks users to acknowledge the GTMBA Project Office of NOAA/PMEL.

• Climate Reanalyzer, University of Maine · NOAA OISST v2.1

  oisst2.1_nino3.4_sst_day.json

  CC BY 4.0. Climate Reanalyzer, Climate Change Institute, University of Maine; underlying data NOAA OISST v2.1.

• Copernicus Climate Change Service / ECMWF (ERA5)

  era5_daily_series_2t_global.csv, era5_daily_series_sst_60S-60N_ocean.csv, climpulse_status.json

  CC BY 4.0. Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.

• International Research Institute for Climate and Society, Columbia University

  figure4_plot

  CC BY 4.0. ENSO Forecast Data © 2002-2026 by International Research Institute for Climate and Society is licensed under Creative Commons Attribution 4.0 International. Values read from the published figure; redrawn by FloodRadar.

• NOAA OISST v2.1

  Huang et al. 2020, doi:10.1175/JCLI-D-20-0166.1. Daily Niño 3.4: ClimateReanalyzer.org, Climate Change Institute, University of Maine · NOAA OISST 2.1 (FloodRadar calculation).

• Britain: the winters, the live figures and the rainfall normals

  Environment Agency flood alerts and warnings (FloodRadar’s archive since 2006) and Environment Agency river and rainfall readings, under the Open Government Licence v3.0. Scottish rain gauges: contains SEPA data © Scottish Environment Protection Agency and database right 2025. Average rainfall: Met Office HadUK-Grid 1991–2020 monthly normals; contains public sector information licensed under the Open Government Licence v3.0. More on FloodRadar’s data sources.

• Met Office

  Quoted on this page: An ‘unprecedented’ El Niño and its implications for the weather forecast (21 August 2026), and the Met Office line carried on El Niño 2026–27, explained, whose source list names each item.

• The globe

  Earth textures from the three.js examples (MIT); three.js r160 (MIT). Coastlines on the air-temperature map drawn by FloodRadar from the same Earth texture.

FloodRadar is not part of NOAA, IRI, Copernicus or ECMWF, and nothing on this page is an official product of any of them. Every record, rank and count is FloodRadar’s own reading of their files, and says so where it appears.