Sønderborg climate — normals and trends
Sønderborg (Denmark) has a temperate oceanic climate (Cfb) under the Köppen-Geiger classification. Its mean annual temperature is 8.7 °C and it receives 641 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 (16.9 °C on average) and the coldest is January (1.0 °C). Rainfall peaks in August.
Sønderborg averages 59 frost days, 0 hot days (≥ 30 °C) and 132 rainy days per year.
Sønderborg has warmed by +2.1 °C between 1940 and 2025, or +0.24 °C per decade. This trend is statistically significant.
The number of frost days there went from about 81 to 37 per year over the period.
The hottest day of the period reached 33.6 °C (on 20 July 2022) and the coldest -20.9 °C (on 26 January 1942).
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
SønderborgSouth Denmark
- coords
- 54.91°, 9.79°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
8.7°C
Average daily high
11.3°C
Average daily low
6.1°C
Annual rainfall
641mm
Sunshine / day
7.7h
Mean relative humidity
82%
Average peak wind
23.3km/h
Seasonal range
15.9°C
Frost days (< 0 °C)
59 d/yr
Hot days (≥ 30 °C)
0 d/yr
Rainy days (≥ 1 mm)
132 d/yr
Annual snowfall
39.0 cm
Average feels-like high
8.1 °C
Average feels-like low
2.5 °C
Average peak gust
43.8 km/h
Tropical nights (≥ 20 °C)
0 d/yr
Solar radiation
10.3 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.1 °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
33.6 °C
20 July 2022
Coldest day
-20.9 °C
26 January 1942
Wettest day
56 mm
25 July 2015
Windiest day
70.9 km/h
3 December 1999
Strongest gust
138.2 km/h
3 December 1999
Hottest feels-like
34.8 °C
20 July 2022
Coldest feels-like
-26.2 °C
25 January 1942
Snowiest day
13.9 cm
21 November 1971
Sunniest day
16.9 h
21 June 2025
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 | 4.7 °C | +2.1 °C | 75 mm | +20 mm |
| Feb | 4.0 °C | +1.1 °C | 15 mm | -27 mm |
| Mar | 9.8 °C | +4.1 °C | 10 mm | -35 mm |
| Apr | 13.5 °C | +3.4 °C | 33 mm | -10 mm |
| May | 16.5 °C | +1.7 °C | 33 mm | -18 mm |
| Jun | 19.8 °C | +1.4 °C | 76 mm | +19 mm |
| Jul | 21.9 °C | +1.6 °C | 102 mm | +37 mm |
| Aug | 21.4 °C | +1.2 °C | 41 mm | -25 mm |
| Sep | 18.6 °C | +1.7 °C | 46 mm | -9 mm |
| Oct | 13.1 °C | +0.9 °C | 91 mm | +35 mm |
| Nov | 8.0 °C | +0.8 °C | 39 mm | -15 mm |
| Dec | 6.9 °C | +2.7 °C | 28 mm | -25 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 Sønderborg?
Sønderborg has a temperate oceanic climate (Köppen Cfb). Over 1940-2025, the average annual temperature is 8.7 °C and it receives 641 mm of precipitation per year.
What is the hottest day ever recorded in Sønderborg?
The hottest day measured in Sønderborg between 1940 and 2025 was 20 July 2022, reaching 33.6 °C.
What is the coldest day in Sønderborg?
The coldest day measured in Sønderborg between 1940 and 2025 was 26 January 1942, at -20.9 °C.
Does it snow in Sønderborg?
Yes. Sønderborg gets on average 39.0 cm of snow per year and has around 59 frost days.
Has the climate of Sønderborg warmed?
Yes: Sønderborg warmed by +2.1 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Sønderborg?
The wettest day measured in Sønderborg between 1940 and 2025 was 25 July 2015, with 56 mm of rain in 24 hours.
What was the windiest day in Sønderborg?
The windiest day measured in Sønderborg between 1940 and 2025 was 3 December 1999, with winds reaching 70.9 km/h.
What is the warmest month in Sønderborg?
The warmest month in Sønderborg is July (16.9 °C on average); the coldest is January (1.0 °C).
How much does it rain in Sønderborg?
Sønderborg receives on average 641 mm of precipitation per year, spread over about 132 rainy days.
Is it sunny in Sønderborg?
Sønderborg gets on average 7.7 hours of sunshine per day, roughly 2,811 hours per year over 1940-2025.
What is the biggest single-day snowfall in Sønderborg?
The heaviest 24-hour snowfall measured in Sønderborg between 1940 and 2025 was 21 November 1971, with 13.9 cm.
Are there tropical nights in Sønderborg?
Almost never: tropical nights (temperature staying above 20 °C) are virtually non-existent in Sønderborg.
What was the most extreme apparent temperature in Sønderborg?
In Sønderborg, between 1940 and 2025, the highest apparent temperature reached 34.8 °C on 20 July 2022, and the lowest was -26.2 °C on 25 January 1942.
Compare Sønderborg with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Sønderborg