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Na h-Eileanan Siar sits in the Met Office's northern Scotland area. Each bar is one year's total; the dark line is the ten-year average, which is what a trend looks like once single wet and dry years are smoothed out; the dashed line is the 1991–2020 average of 1,701 mm. 2025 brought 1,470 mm, close to that. The wettest year here since 1996 was 2011 (1,971 mm), the driest 2010 (1,275 mm).
Rainfall over a whole region, not a measurement in Na h-Eileanan Siar itself, and a wet year is not the same thing as a flood: what floods a river is how much falls at once and how wet the ground already was. Average rainfall: HadUK-Grid v1.3.2, Met Office. Contains public sector information licensed under the Open Government Licence v3.0.
Rain gauge totals for the last day, week and month, by town:
Year by year, each figure divided by what changed about the measuring — the gauge fleet, the flood areas on the register, the overflows monitored.
Na h-Eileanan Siar, Environment Agency, SEPA and NRW gauges, 2016–2025
The last 5 years average 80.0%, against 35.0% for the first 5 — 129% higher.
El Niño winter La Niña winter. Marked for context, not as a cause — these are states of the Pacific, and one wet fortnight moves a British year more than a whole season's pattern does. What El Niño and La Niña are, and what they did here.
The raw count went from 1 to 4 gauges with a high day between 2016 and 2025, divided every year by the same 4 gauges reporting — which is what makes the two ends comparable.
Each gauge's high level was last re-fitted on 2 October 2026, over that gauge's whole record. It is re-fitted monthly, so these percentages can move a little between rebuilds even in a week with no rain.
What this chart finds is BUNCHING — years when many gauges reached their own high level at once. It cannot tell you whether rivers run higher than they used to, and here is why: each gauge is measured against the level it itself reaches about one day a year over its own whole record, so every gauge crosses that bar about once a year by construction, however wet or dry its river has become. The bar is re-fitted every month as records grow, so a wet decade raises it and damps the very rise you are looking for. Dividing by the gauges that reported keeps the growing fleet out of the count; the like-for-like chart below holds the gauges themselves fixed as well.
See all four across the whole UK, and how to read them
Rebuilt on 5 October 2026, from data banked up to the end of 2026. Only whole calendar years are counted, so 2026 will appear here once it has finished. The rebuild runs weekly.
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