Four things, measured year by year: how much rain fell, how often rivers
reached a level they rarely reach, how often flood alerts went out, and how often sewage
overflows spilled. For the UK.
Three of these four are counted better every year, so the raw numbers
climb whether or not the weather does. Flood alerts rose roughly fivefold since 2006 —
and so did the number of places that can be sent one. Every chart below divides by what
changed, and says what it divided by.
Rainfall
United Kingdom, by region and country · 1926–2025
The last 50 years average 1,150mm, against 1,067mm for the first 50 — 8% higher.
The one series here that needs no adjusting: the Met Office has measured areal rainfall the same way since 1836, so a tall bar is a wet year and nothing else. It is an average over a whole region, not a reading from your street.
River gauges reaching a high level
Great Britain, from 1990 · 1990–2025
The last 18 years average 47.8%, against 37.3% for the first 18 — 28% higher.
The raw count went from 189
to 1,502 gauges with a high day — but the gauges reporting went from 528
to 2,750, which is what the chart divides by.
The gauge fleet grew from 531 in 1990 to 3,051 in 2025, so a count of gauges would mostly measure the fleet. This is the SHARE of the gauges that reported in a year which reached a level they themselves reach about one day in a year. Each gauge is judged against its own history, never against another. One bias remains and it leans recent: a gauge installed in 2015 has its high level fitted to 2015 onwards, so newer gauges reach it about once a year by construction, while a gauge with a forty-year record is measured against all forty. The like-for-like chart below removes that; trust it over this one.
The same gauges, every year
The last 12 years average 51.7%, against 40.3% for the first 12 — 28% higher.
The strictest read, and the one to believe: the SAME gauges every year, each reporting nearly every day of every year in the window, so neither the fleet nor the way the high level was fitted can move underneath the line. A few hundred long-serving gauges rather than the whole fleet, so it is a narrower sample of the country than the chart above.
Flood alerts and warnings
England, from 2006 (Environment Agency) · 2006–2025
Little changed: the first 10 years average 3.87 per area and the last 10 average 4.05 per area.
The raw count went from 2,241
to 4,249 alerts and warnings — but the areas warned went from 416
to 1,279, which is what the chart divides by.
Raw warning counts rose roughly fivefold since 2006, but so did the number of flood areas that can be warned — 415 areas were warned in 2006 and 1,780 in 2024. This chart divides by the areas actually warned, which is the part that is about the weather rather than about the register. Warning policy also changed over the period.
The last 2 years average 32.2 spills, against 25.8 spills for the first 2 — 25% higher.
The raw count went from 309,409
to 450,398 spills — but the monitored overflows went from 10,542
to 14,182, which is what the chart divides by.
Only four years exist, so this is a comparison and not a trend. Monitored overflows grew from 10,542 to 14,182 across them, which is why the figure is per overflow. Spills also track the weather: 2022 was a dry year.
The same overflows, every year
The last 2 years average 32.3 spills, against 26.0 spills for the first 2 — 24% higher.
Only the overflows that filed a return in all four years, so the monitor rollout cannot move the line. Still four years, so still a comparison.
How to read these charts
Each bar is one year. The dark line over them is a rolling average, which is the part
worth looking at — a single year is weather, and one wet fortnight moves a whole year.
The dashed line is the long-run average for that place.
Hover or tap a bar to see the working: the published figure, the raw count behind it, and
the number it was divided by.
What these charts cannot tell you
Why. Nothing here attributes anything to climate change, to river
management, or to anything else. They are counts of what was recorded.
Your street. Rainfall is a regional average and gauges sit where the
Environment Agency put them, not where you live. For one place, start at
flood risk near you.
Anything before the record starts. The Met Office rainfall record
runs back to 1836 and the chart above draws the most recent century of it; flood
warnings only start in 2006, and sewage monitoring in 2021. A chart that begins in
2006 means nobody was counting before then, not that nothing happened.
Where these numbers come from
Rainfall — Met Office HadUK-Grid areal series, 1836 onwards.
Contains public sector information licensed under the Open Government Licence v3.0.
River gauges — FloodRadar's own banked daily maxima from Environment
Agency, SEPA and Natural Resources Wales gauges, each compared with that gauge's own
history. See data sources.
Flood alerts and warnings — the Environment Agency warning archive
FloodRadar has banked since 2006. England only.
