Mountain Ash climate — normals and trends
Mountain Ash (United Kingdom) has a temperate oceanic climate (Cfb) under the Köppen-Geiger classification. Its mean annual temperature is 9.0 °C and it receives 1,090 mm of precipitation per year.
These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.
The warmest month is July (15.0 °C on average) and the coldest is January (3.5 °C). Rainfall peaks in December.
Mountain Ash averages 46 frost days, 0 hot days (≥ 30 °C) and 164 rainy days per year.
Mountain Ash has warmed by +1.6 °C between 1940 and 2025, or +0.18 °C per decade. This trend is statistically significant.
The number of frost days there went from about 61 to 31 per year over the period.
The hottest day of the period reached 32.5 °C (on 18 July 2022) and the coldest -20.0 °C (on 21 January 1940).
Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.
Climate normals · ERA5
Mountain AshWales
- coords
- 51.68°, -3.38°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
9.0°C
Average daily high
11.9°C
Average daily low
5.9°C
Annual rainfall
1,090mm
Sunshine / day
8.0h
Mean relative humidity
85%
Average peak wind
20.7km/h
Seasonal range
11.5°C
Frost days (< 0 °C)
46 d/yr
Hot days (≥ 30 °C)
0 d/yr
Rainy days (≥ 1 mm)
164 d/yr
Annual snowfall
27.5 cm
Average feels-like high
9.1 °C
Average feels-like low
2.9 °C
Average peak gust
44.9 km/h
Tropical nights (≥ 20 °C)
0 d/yr
Solar radiation
10.8 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.6 °C
since 1940
+0.2 °C per decade · r² = 0.41 · p = < 0.001
Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).
A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.
Records for the period
Hottest day
32.5 °C
18 July 2022
Coldest day
-20.0 °C
21 January 1940
Wettest day
64 mm
27 December 1979
Windiest day
60.9 km/h
30 November 1954
Strongest gust
150.8 km/h
25 January 1990
Hottest feels-like
33.1 °C
18 July 2022
Coldest feels-like
-24.7 °C
21 January 1940
Snowiest day
30.3 cm
8 January 1982
Sunniest day
16.0 h
14 June 2022
Normals computed over complete calendar years 1940–2025.
A specific year
Pick a year and see how it compares to normal — warmer, drier or more extreme than usual?
Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | 6.1 °C | +0.4 °C | 139 mm | +36 mm |
| Feb | 6.8 °C | +0.8 °C | 100 mm | +16 mm |
| Mar | 11.1 °C | +2.8 °C | 22 mm | -60 mm |
| Apr | 14.4 °C | +3.4 °C | 80 mm | +5 mm |
| May | 16.9 °C | +2.8 °C | 48 mm | -42 mm |
| Jun | 18.4 °C | +1.6 °C | 95 mm | +19 mm |
| Jul | 20.5 °C | +2.1 °C | 59 mm | -21 mm |
| Aug | 20.3 °C | +2.2 °C | 58 mm | -32 mm |
| Sep | 15.8 °C | -0.2 °C | 160 mm | +71 mm |
| Oct | 12.9 °C | +0.3 °C | 122 mm | +14 mm |
| Nov | 10.3 °C | +1.5 °C | 211 mm | +108 mm |
| Dec | 8.3 °C | +1.7 °C | 202 mm | +91 mm |
The year's extremes
What was the weather like that day?
Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.
Frequently asked questions
What is the climate of Mountain Ash?
Mountain Ash has a temperate oceanic climate (Köppen Cfb). Over 1940-2025, the average annual temperature is 9.0 °C and it receives 1,090 mm of precipitation per year.
What is the hottest day ever recorded in Mountain Ash?
The hottest day measured in Mountain Ash between 1940 and 2025 was 18 July 2022, reaching 32.5 °C.
What is the coldest day in Mountain Ash?
The coldest day measured in Mountain Ash between 1940 and 2025 was 21 January 1940, at -20.0 °C.
Does it snow in Mountain Ash?
Yes. Mountain Ash gets on average 27.5 cm of snow per year and has around 46 frost days.
Has the climate of Mountain Ash warmed?
Yes: Mountain Ash warmed by +1.6 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Mountain Ash?
The wettest day measured in Mountain Ash between 1940 and 2025 was 27 December 1979, with 64 mm of rain in 24 hours.
What was the windiest day in Mountain Ash?
The windiest day measured in Mountain Ash between 1940 and 2025 was 30 November 1954, with winds reaching 60.9 km/h.
What is the warmest month in Mountain Ash?
The warmest month in Mountain Ash is July (15.0 °C on average); the coldest is January (3.5 °C).
How much does it rain in Mountain Ash?
Mountain Ash receives on average 1,090 mm of precipitation per year, spread over about 164 rainy days.
Is it sunny in Mountain Ash?
Mountain Ash gets on average 8.0 hours of sunshine per day, roughly 2,920 hours per year over 1940-2025.
What is the biggest single-day snowfall in Mountain Ash?
The heaviest 24-hour snowfall measured in Mountain Ash between 1940 and 2025 was 8 January 1982, with 30.3 cm.
Are there tropical nights in Mountain Ash?
Almost never: tropical nights (temperature staying above 20 °C) are virtually non-existent in Mountain Ash.
What was the most extreme apparent temperature in Mountain Ash?
In Mountain Ash, between 1940 and 2025, the highest apparent temperature reached 33.1 °C on 18 July 2022, and the lowest was -24.7 °C on 21 January 1940.
Compare Mountain Ash with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Mountain Ash