Caernarfon climate — normals and trends
Caernarfon (United Kingdom) has a temperate oceanic climate (Cfb) under the Köppen-Geiger classification. Its mean annual temperature is 9.9 °C and it receives 978 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 (15.4 °C on average) and the coldest is January (5.0 °C). Rainfall peaks in December.
Caernarfon averages 23 frost days, 0 hot days (≥ 30 °C) and 179 rainy days per year.
Caernarfon has warmed by +1.4 °C between 1940 and 2025, or +0.16 °C per decade. This trend is statistically significant.
The number of frost days there went from about 35 to 11 per year over the period.
The hottest day of the period reached 32.5 °C (on 18 July 2022) and the coldest -13.8 °C (on 26 January 1945).
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
CaernarfonWales
- coords
- 53.14°, -4.27°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
9.9°C
Average daily high
12.5°C
Average daily low
7.2°C
Annual rainfall
978mm
Sunshine / day
8.0h
Mean relative humidity
82%
Average peak wind
23.2km/h
Seasonal range
10.4°C
Frost days (< 0 °C)
23 d/yr
Hot days (≥ 30 °C)
0 d/yr
Rainy days (≥ 1 mm)
179 d/yr
Annual snowfall
13.8 cm
Average feels-like high
9.6 °C
Average feels-like low
3.9 °C
Average peak gust
48.7 km/h
Tropical nights (≥ 20 °C)
0 d/yr
Solar radiation
10.6 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.4 °C
since 1940
+0.2 °C per decade · r² = 0.37 · 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
-13.8 °C
26 January 1945
Wettest day
53 mm
21 September 2007
Windiest day
74.4 km/h
24 December 1997
Strongest gust
166.7 km/h
24 December 1997
Hottest feels-like
35.2 °C
29 July 1948
Coldest feels-like
-18.3 °C
26 January 1945
Snowiest day
14.3 cm
16 January 1955
Sunniest day
16.5 h
27 June 2005
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 | 6.9 °C | -0.1 °C | 119 mm | +31 mm |
| Feb | 8.0 °C | +0.8 °C | 52 mm | -20 mm |
| Mar | 11.4 °C | +2.4 °C | 24 mm | -50 mm |
| Apr | 15.0 °C | +3.7 °C | 83 mm | +13 mm |
| May | 16.7 °C | +2.4 °C | 42 mm | -32 mm |
| Jun | 17.9 °C | +1.0 °C | 109 mm | +39 mm |
| Jul | 19.7 °C | +1.4 °C | 66 mm | -8 mm |
| Aug | 20.3 °C | +2.1 °C | 42 mm | -42 mm |
| Sep | 16.5 °C | +0.2 °C | 143 mm | +59 mm |
| Oct | 13.5 °C | +0.2 °C | 94 mm | -0 mm |
| Nov | 11.2 °C | +1.3 °C | 188 mm | +90 mm |
| Dec | 9.3 °C | +1.3 °C | 137 mm | +39 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 Caernarfon?
Caernarfon has a temperate oceanic climate (Köppen Cfb). Over 1940-2025, the average annual temperature is 9.9 °C and it receives 978 mm of precipitation per year.
What is the hottest day ever recorded in Caernarfon?
The hottest day measured in Caernarfon between 1940 and 2025 was 18 July 2022, reaching 32.5 °C.
What is the coldest day in Caernarfon?
The coldest day measured in Caernarfon between 1940 and 2025 was 26 January 1945, at -13.8 °C.
Does it snow in Caernarfon?
Yes. Caernarfon gets on average 13.8 cm of snow per year and has around 23 frost days.
Has the climate of Caernarfon warmed?
Yes: Caernarfon warmed by +1.4 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Caernarfon?
The wettest day measured in Caernarfon between 1940 and 2025 was 21 September 2007, with 53 mm of rain in 24 hours.
What was the windiest day in Caernarfon?
The windiest day measured in Caernarfon between 1940 and 2025 was 24 December 1997, with winds reaching 74.4 km/h.
What is the warmest month in Caernarfon?
The warmest month in Caernarfon is July (15.4 °C on average); the coldest is January (5.0 °C).
How much does it rain in Caernarfon?
Caernarfon receives on average 978 mm of precipitation per year, spread over about 179 rainy days.
Is it sunny in Caernarfon?
Caernarfon 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 Caernarfon?
The heaviest 24-hour snowfall measured in Caernarfon between 1940 and 2025 was 16 January 1955, with 14.3 cm.
Are there tropical nights in Caernarfon?
Almost never: tropical nights (temperature staying above 20 °C) are virtually non-existent in Caernarfon.
What was the most extreme apparent temperature in Caernarfon?
In Caernarfon, between 1940 and 2025, the highest apparent temperature reached 35.2 °C on 29 July 1948, and the lowest was -18.3 °C on 26 January 1945.
Compare Caernarfon with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Caernarfon