Cwmystwyth historic rainfall: records, monthly averages and yearly totals

Rainfall in Cwmystwyth (1959–2026)

The mean annual precipitation in Cwmystwyth is 1662.8 mm, based on the Met Office historical record for the period 1959–2026. That places this upland area of mid-Wales among the wetter locations in the United Kingdom, with rain falling on a large share of days throughout the year.

The seasonal distribution shows a clear autumn and winter maximum. Autumn months together account for 531 mm, winter for 516 mm, summer for 368 mm and spring for 340 mm. December is the wettest month on average with 206.27903225806452 mm, while April is the driest with 99.35 mm. The number of rain days follows the same pattern: December and November both average 18.3 days with more than 1 mm, against 13.0 days in April.

Average rainfall by month

The wettest month is December with a mean monthly rainfall of 206.27903225806452 mm, and the driest is April with 99.35 mm. The December daily record of 121.9 mm is also the highest for any month, followed by October with 95.6 mm.

The 5 wettest days on record

Four of the five wettest days occurred in December or October, consistent with the seasonal maximum shown in the monthly averages. The only exception is 1971-06-19, when 90.0 mm fell in a single June day.

Annual rainfall totals

The chart shows the complete annual series. The table lists the most notable years; the full series comes from Met Office.

The table above shows the full annual series for the cwmystwyth station. Years such as 2000, with 2564.3 mm, and 1998, with 2284.6 mm, stand out as particularly wet. The year 2011, with 749.7 mm, is the driest in the series. Note that 2022 includes only 1.6 mm and 1 rain day, and 2026 includes 35.0 mm and 5 rain days, as these years contain incomplete records within the analysed period.

Frequently asked questions

How much rain falls per year in Cwmystwyth?

1662.8 mm of mean annual precipitation, based on the cwmystwyth Met Office station for the period 1959–2026. This makes Cwmystwyth considerably wetter than most of lowland England and Wales, reflecting its upland location in the Cambrian Mountains.

How many rainy days are there per year in Cwmystwyth?

173.8 days of rain per year on average (days with precipitation >1 mm). In practice, this means that roughly every other day brings measurable rainfall, although intensity varies widely between seasons.

Which month is the wettest in Cwmystwyth?

December is the wettest month with a mean monthly rainfall of 206.27903225806452 mm. November follows with 198.32419354838711 mm and October with 183.6079365079365 mm. April is the driest month with 99.35 mm.

What was the wettest day ever recorded in Cwmystwyth?

The wettest day in the station's record is 1964-12-13, when 121.9 mm of precipitation fell in a single day. This value is the highest daily total in the series and also the daily record for December.

Is Cwmystwyth a rainy area?

Yes, it is. With a mean annual precipitation of 1662.8 mm and an average of 173.8 rain days per year, Cwmystwyth ranks among the wetter stations in Wales. The seasonal pattern is typical of western Britain: autumn and winter receive the most rainfall, with 531 mm and 516 mm respectively, while spring is the driest season at 340 mm.