Altena climate — normals and trends
Altena (Germany) has a temperate oceanic climate (Cfb) under the Köppen-Geiger classification. Its mean annual temperature is 8.3 °C and it receives 1,077 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 (16.5 °C on average) and the coldest is January (0.0 °C). Rainfall peaks in July.
Altena averages 74 frost days, 2 hot days (≥ 30 °C) and 177 rainy days per year.
Altena has warmed by +2.1 °C between 1940 and 2025, or +0.25 °C per decade. This trend is statistically significant.
The number of frost days there went from about 92 to 56 per year over the period.
The hottest day of the period reached 35.7 °C (on 25 July 2019) and the coldest -23.6 °C (on 27 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
AltenaNorth Rhine-Westphalia
- coords
- 51.29°, 7.67°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
8.3°C
Average daily high
11.6°C
Average daily low
5.3°C
Annual rainfall
1,077mm
Sunshine / day
7.4h
Mean relative humidity
82%
Average peak wind
18.5km/h
Seasonal range
16.5°C
Frost days (< 0 °C)
74 d/yr
Hot days (≥ 30 °C)
2 d/yr
Rainy days (≥ 1 mm)
177 d/yr
Annual snowfall
84.2 cm
Average feels-like high
8.9 °C
Average feels-like low
2.1 °C
Average peak gust
39.3 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
+0.3 °C per decade · r² = 0.43 · 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
35.7 °C
25 July 2019
Coldest day
-23.6 °C
27 January 1942
Wettest day
94 mm
14 July 2021
Windiest day
55.2 km/h
18 January 2007
Strongest gust
133.6 km/h
24 November 1984
Hottest feels-like
38.0 °C
25 July 2019
Coldest feels-like
-28.6 °C
27 January 1942
Snowiest day
20.4 cm
27 November 1949
Sunniest day
15.4 h
30 June 2018
Normals computed over complete calendar years 1940–2025.
A specific year
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Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | 3.4 °C | +1.4 °C | 168 mm | +72 mm |
| Feb | 5.2 °C | +2.0 °C | 32 mm | -49 mm |
| Mar | 11.7 °C | +4.4 °C | 25 mm | -60 mm |
| Apr | 15.5 °C | +3.9 °C | 91 mm | +13 mm |
| May | 18.5 °C | +2.6 °C | 60 mm | -28 mm |
| Jun | 22.8 °C | +4.0 °C | 79 mm | -15 mm |
| Jul | 22.9 °C | +2.4 °C | 96 mm | -8 mm |
| Aug | 23.8 °C | +3.5 °C | 45 mm | -52 mm |
| Sep | 18.4 °C | +1.4 °C | 86 mm | +2 mm |
| Oct | 12.0 °C | -0.2 °C | 116 mm | +37 mm |
| Nov | 8.4 °C | +1.8 °C | 66 mm | -24 mm |
| Dec | 6.4 °C | +3.1 °C | 40 mm | -61 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 Altena?
Altena has a temperate oceanic climate (Köppen Cfb). Over 1940-2025, the average annual temperature is 8.3 °C and it receives 1,077 mm of precipitation per year.
What is the hottest day ever recorded in Altena?
The hottest day measured in Altena between 1940 and 2025 was 25 July 2019, reaching 35.7 °C.
What is the coldest day in Altena?
The coldest day measured in Altena between 1940 and 2025 was 27 January 1942, at -23.6 °C.
Does it snow in Altena?
Yes. Altena gets on average 84.2 cm of snow per year and has around 74 frost days.
Has the climate of Altena warmed?
Yes: Altena warmed by +2.1 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Altena?
The wettest day measured in Altena between 1940 and 2025 was 14 July 2021, with 94 mm of rain in 24 hours.
What was the windiest day in Altena?
The windiest day measured in Altena between 1940 and 2025 was 18 January 2007, with winds reaching 55.2 km/h.
What is the warmest month in Altena?
The warmest month in Altena is July (16.5 °C on average); the coldest is January (0.0 °C).
How much does it rain in Altena?
Altena receives on average 1,077 mm of precipitation per year, spread over about 177 rainy days.
Is it sunny in Altena?
Altena gets on average 7.4 hours of sunshine per day, roughly 2,701 hours per year over 1940-2025.
What is the biggest single-day snowfall in Altena?
The heaviest 24-hour snowfall measured in Altena between 1940 and 2025 was 27 November 1949, with 20.4 cm.
Are there tropical nights in Altena?
Almost never: tropical nights (temperature staying above 20 °C) are virtually non-existent in Altena.
What was the most extreme apparent temperature in Altena?
In Altena, between 1940 and 2025, the highest apparent temperature reached 38.0 °C on 25 July 2019, and the lowest was -28.6 °C on 27 January 1942.
Compare Altena with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Altena