Aarau climate — normals and trends
Aarau (Switzerland) has a warm-summer humid continental climate (Dfb) under the Köppen-Geiger classification. Its mean annual temperature is 8.7 °C and it receives 1,358 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 (17.8 °C on average) and the coldest is January (-0.7 °C). Rainfall peaks in June.
Aarau averages 90 frost days, 3 hot days (≥ 30 °C) and 177 rainy days per year.
Aarau has warmed by +2.4 °C between 1940 and 2025, or +0.28 °C per decade. This trend is statistically significant.
The number of frost days there went from about 113 to 67 per year over the period.
The hottest day of the period reached 34.6 °C (on 7 July 2015) and the coldest -26.6 °C (on 13 February 1956).
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
AarauCanton of Aargau
- coords
- 47.39°, 8.04°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
8.7°C
Average daily high
12.6°C
Average daily low
5.0°C
Annual rainfall
1,358mm
Sunshine / day
8.4h
Mean relative humidity
79%
Average peak wind
11.9km/h
Seasonal range
18.5°C
Frost days (< 0 °C)
90 d/yr
Hot days (≥ 30 °C)
3 d/yr
Rainy days (≥ 1 mm)
177 d/yr
Annual snowfall
103.2 cm
Average feels-like high
10.8 °C
Average feels-like low
2.8 °C
Average peak gust
30.8 km/h
Tropical nights (≥ 20 °C)
0 d/yr
Solar radiation
12.1 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.4 °C
since 1940
+0.3 °C per decade · r² = 0.57 · 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
34.6 °C
7 July 2015
Coldest day
-26.6 °C
13 February 1956
Wettest day
61 mm
14 February 1990
Windiest day
53.1 km/h
26 December 1999
Strongest gust
137.5 km/h
26 December 1999
Hottest feels-like
38.6 °C
27 June 2019
Coldest feels-like
-30.8 °C
13 February 1956
Snowiest day
27.0 cm
4 March 2006
Sunniest day
15.0 h
20 May 1940
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 | 4.5 °C | +2.4 °C | 135 mm | +39 mm |
| Feb | 5.5 °C | +1.2 °C | 64 mm | -23 mm |
| Mar | 11.5 °C | +2.6 °C | 65 mm | -30 mm |
| Apr | 16.2 °C | +3.3 °C | 78 mm | -27 mm |
| May | 18.4 °C | +1.3 °C | 123 mm | -19 mm |
| Jun | 25.8 °C | +5.3 °C | 134 mm | -9 mm |
| Jul | 23.2 °C | +0.6 °C | 171 mm | +29 mm |
| Aug | 24.9 °C | +2.9 °C | 218 mm | +74 mm |
| Sep | 18.6 °C | +0.2 °C | 174 mm | +69 mm |
| Oct | 13.1 °C | 0.0 °C | 145 mm | +53 mm |
| Nov | 7.5 °C | +0.8 °C | 119 mm | +15 mm |
| Dec | 4.4 °C | +1.4 °C | 32 mm | -72 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 Aarau?
Aarau has a warm-summer humid continental climate (Köppen Dfb). Over 1940-2025, the average annual temperature is 8.7 °C and it receives 1,358 mm of precipitation per year.
What is the hottest day ever recorded in Aarau?
The hottest day measured in Aarau between 1940 and 2025 was 7 July 2015, reaching 34.6 °C.
What is the coldest day in Aarau?
The coldest day measured in Aarau between 1940 and 2025 was 13 February 1956, at -26.6 °C.
Does it snow in Aarau?
Yes. Aarau gets on average 103.2 cm of snow per year and has around 90 frost days.
Has the climate of Aarau warmed?
Yes: Aarau warmed by +2.4 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Aarau?
The wettest day measured in Aarau between 1940 and 2025 was 14 February 1990, with 61 mm of rain in 24 hours.
What was the windiest day in Aarau?
The windiest day measured in Aarau between 1940 and 2025 was 26 December 1999, with winds reaching 53.1 km/h.
What is the warmest month in Aarau?
The warmest month in Aarau is July (17.8 °C on average); the coldest is January (-0.7 °C).
How much does it rain in Aarau?
Aarau receives on average 1,358 mm of precipitation per year, spread over about 177 rainy days.
Is it sunny in Aarau?
Aarau gets on average 8.4 hours of sunshine per day, roughly 3,066 hours per year over 1940-2025.
What is the biggest single-day snowfall in Aarau?
The heaviest 24-hour snowfall measured in Aarau between 1940 and 2025 was 4 March 2006, with 27.0 cm.
Are there tropical nights in Aarau?
Almost never: tropical nights (temperature staying above 20 °C) are virtually non-existent in Aarau.
What was the most extreme apparent temperature in Aarau?
In Aarau, between 1940 and 2025, the highest apparent temperature reached 38.6 °C on 27 June 2019, and the lowest was -30.8 °C on 13 February 1956.
Compare Aarau with another city
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Nearby cities
The climate around Aarau