Dumbarton climate — normals and trends
Dumbarton (United Kingdom) has a temperate oceanic climate (Cfb) under the Köppen-Geiger classification. Its mean annual temperature is 8.3 °C and it receives 1,301 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 (14.1 °C on average) and the coldest is January (3.0 °C). Rainfall peaks in October.
Dumbarton averages 52 frost days, 0 hot days (≥ 30 °C) and 189 rainy days per year.
Dumbarton has warmed by +1.8 °C between 1940 and 2025, or +0.22 °C per decade. This trend is statistically significant.
The number of frost days there went from about 73 to 31 per year over the period.
The hottest day of the period reached 29.1 °C (on 4 August 1975) and the coldest -20.4 °C (on 1 March 1947).
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
DumbartonScotland
- coords
- 55.94°, -4.57°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
8.3°C
Average daily high
11.1°C
Average daily low
5.4°C
Annual rainfall
1,301mm
Sunshine / day
6.7h
Mean relative humidity
84%
Average peak wind
19.1km/h
Seasonal range
11.1°C
Frost days (< 0 °C)
52 d/yr
Hot days (≥ 30 °C)
0 d/yr
Rainy days (≥ 1 mm)
189 d/yr
Annual snowfall
51.9 cm
Average feels-like high
8.3 °C
Average feels-like low
2.4 °C
Average peak gust
45.0 km/h
Tropical nights (≥ 20 °C)
0 d/yr
Solar radiation
8.7 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.8 °C
since 1940
+0.2 °C per decade · r² = 0.48 · 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
29.1 °C
4 August 1975
Coldest day
-20.4 °C
1 March 1947
Wettest day
65 mm
10 August 2004
Windiest day
62.5 km/h
15 January 1968
Strongest gust
153.0 km/h
28 January 2002
Hottest feels-like
30.3 °C
28 June 2018
Coldest feels-like
-25.1 °C
1 March 1947
Snowiest day
19.0 cm
25 January 1990
Sunniest day
17.0 h
19 June 1940
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 | 5.7 °C | +0.5 °C | 68 mm | -61 mm |
| Feb | 7.2 °C | +1.5 °C | 116 mm | +12 mm |
| Mar | 10.8 °C | +3.0 °C | 53 mm | -50 mm |
| Apr | 13.8 °C | +3.4 °C | 47 mm | -33 mm |
| May | 17.0 °C | +3.5 °C | 74 mm | -14 mm |
| Jun | 16.5 °C | +0.6 °C | 122 mm | +38 mm |
| Jul | 18.9 °C | +1.7 °C | 81 mm | -13 mm |
| Aug | 18.9 °C | +1.9 °C | 111 mm | +1 mm |
| Sep | 15.2 °C | +0.4 °C | 132 mm | +16 mm |
| Oct | 12.3 °C | +0.6 °C | 169 mm | +34 mm |
| Nov | 9.1 °C | +1.1 °C | 187 mm | +64 mm |
| Dec | 7.8 °C | +1.8 °C | 191 mm | +55 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 Dumbarton?
Dumbarton has a temperate oceanic climate (Köppen Cfb). Over 1940-2025, the average annual temperature is 8.3 °C and it receives 1,301 mm of precipitation per year.
What is the hottest day ever recorded in Dumbarton?
The hottest day measured in Dumbarton between 1940 and 2025 was 4 August 1975, reaching 29.1 °C.
What is the coldest day in Dumbarton?
The coldest day measured in Dumbarton between 1940 and 2025 was 1 March 1947, at -20.4 °C.
Does it snow in Dumbarton?
Yes. Dumbarton gets on average 51.9 cm of snow per year and has around 52 frost days.
Has the climate of Dumbarton warmed?
Yes: Dumbarton warmed by +1.8 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Dumbarton?
The wettest day measured in Dumbarton between 1940 and 2025 was 10 August 2004, with 65 mm of rain in 24 hours.
What was the windiest day in Dumbarton?
The windiest day measured in Dumbarton between 1940 and 2025 was 15 January 1968, with winds reaching 62.5 km/h.
What is the warmest month in Dumbarton?
The warmest month in Dumbarton is July (14.1 °C on average); the coldest is January (3.0 °C).
How much does it rain in Dumbarton?
Dumbarton receives on average 1,301 mm of precipitation per year, spread over about 189 rainy days.
Is it sunny in Dumbarton?
Dumbarton gets on average 6.7 hours of sunshine per day, roughly 2,446 hours per year over 1940-2025.
What is the biggest single-day snowfall in Dumbarton?
The heaviest 24-hour snowfall measured in Dumbarton between 1940 and 2025 was 25 January 1990, with 19.0 cm.
Are there tropical nights in Dumbarton?
Almost never: tropical nights (temperature staying above 20 °C) are virtually non-existent in Dumbarton.
What was the most extreme apparent temperature in Dumbarton?
In Dumbarton, between 1940 and 2025, the highest apparent temperature reached 30.3 °C on 28 June 2018, and the lowest was -25.1 °C on 1 March 1947.
Compare Dumbarton with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Dumbarton