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Aarau, Switzerland climate
Cfb Oceanic / temperate
Aarau has a seasonal cool-temperate climate (Oceanic / temperate, Köppen Cfb). The hottest month is July with an average daily high near 26°C, while the coldest is January averaging around −2°C at night. Precipitation is fairly even year-round, totalling about 920 mm.
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Summers
Warm
Highs near 26°C in July.
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Winters
Cold
Lows near −2°C in January.
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Rain
Moderate rainfall
About 920 mm of rain a year.
Wettest in May
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Sky & trend
Often cloudy
Cloudy skies much of the year.
Temperature & precipitation
Daily high–low temperature range with the monthly average, plus monthly precipitation · 1991–2020 normals · hover a month for the exact figuresHours of sunshine per day
Estimated sunny hours each month — daylight length × clear-sky fraction · 1991–2020 monthly cloud cover (NASA POWER)Aarau climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 4 | 6 | 11 | 16 | 20 | 24 | 26 | 25 | 20 | 15 | 8 | 4 |
| Avg temp (°C) | 1 | 2 | 6 | 10 | 14 | 18 | 19 | 19 | 15 | 10 | 5 | 2 |
| Avg low (°C) | −2 | −2 | 1 | 4 | 9 | 12 | 14 | 14 | 10 | 7 | 2 | −1 |
| Precipitation (mm) | 63 | 53 | 61 | 63 | 99 | 92 | 98 | 98 | 70 | 72 | 69 | 81 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°C) | 4 | 6 | 11 | 16 | 20 | 24 |
| Avg temp (°C) | 1 | 2 | 6 | 10 | 14 | 18 |
| Avg low (°C) | −2 | −2 | 1 | 4 | 9 | 12 |
| Precipitation (mm) | 63 | 53 | 61 | 63 | 99 | 92 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°C) | 26 | 25 | 20 | 15 | 8 | 4 |
| Avg temp (°C) | 19 | 19 | 15 | 10 | 5 | 2 |
| Avg low (°C) | 14 | 14 | 10 | 7 | 2 | −1 |
| Precipitation (mm) | 98 | 98 | 70 | 72 | 69 | 81 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 69 | 69 | 68 | 67 | 69 | 65 | 60 | 60 | 62 | 68 | 72 | 72 |
| Relative humidity (%) | 89 | 86 | 82 | 79 | 78 | 78 | 77 | 78 | 81 | 85 | 89 | 89 |
| Wind speed (m/s) | 2.2 | 2.3 | 2.3 | 2.0 | 1.9 | 1.8 | 1.7 | 1.5 | 1.7 | 1.8 | 1.8 | 2.1 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 69 | 69 | 68 | 67 | 69 | 65 |
| Relative humidity (%) | 89 | 86 | 82 | 79 | 78 | 78 |
| Wind speed (m/s) | 2.2 | 2.3 | 2.3 | 2.0 | 1.9 | 1.8 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 60 | 60 | 62 | 68 | 72 | 72 |
| Relative humidity (%) | 77 | 78 | 81 | 85 | 89 | 89 |
| Wind speed (m/s) | 1.7 | 1.5 | 1.7 | 1.8 | 1.8 | 2.1 |
Methodology & sources
Temperature & precipitation — the official 1991–2020 climate normals from a national meteorological service, measured at Buchs / Aarau, about 3 km from the city centre.
Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.