Willisau climate — normals and trends
Willisau (Switzerland) has a warm-summer humid continental climate (Dfb) under the Köppen-Geiger classification. Its mean annual temperature is 7.6 °C and it receives 1,543 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 (16.6 °C on average) and the coldest is January (-1.5 °C). Rainfall peaks in July.
Willisau averages 111 frost days, 1 hot days (≥ 30 °C) and 187 rainy days per year.
Willisau has warmed by +2.8 °C between 1940 and 2025, or +0.33 °C per decade. This trend is statistically significant.
The number of frost days there went from about 140 to 82 per year over the period.
The hottest day of the period reached 33.9 °C (on 7 July 2015) and the coldest -23.3 °C (on 23 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
WillisauCanton of Lucerne
- coords
- 47.12°, 7.99°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
7.6°C
Average daily high
11.5°C
Average daily low
3.7°C
Annual rainfall
1,543mm
Sunshine / day
8.7h
Mean relative humidity
79%
Average peak wind
9.0km/h
Seasonal range
18.1°C
Frost days (< 0 °C)
111 d/yr
Hot days (≥ 30 °C)
1 d/yr
Rainy days (≥ 1 mm)
187 d/yr
Annual snowfall
229.0 cm
Average feels-like high
9.9 °C
Average feels-like low
1.4 °C
Average peak gust
30.0 km/h
Tropical nights (≥ 20 °C)
0 d/yr
Solar radiation
12.6 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.8 °C
since 1940
+0.3 °C per decade · r² = 0.67 · 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
33.9 °C
7 July 2015
Coldest day
-23.3 °C
23 January 1942
Wettest day
77 mm
27 September 1942
Windiest day
35.0 km/h
26 December 1999
Strongest gust
136.1 km/h
26 December 1999
Hottest feels-like
36.4 °C
26 June 2019
Coldest feels-like
-29.1 °C
10 February 1956
Snowiest day
23.6 cm
9 February 1999
Sunniest day
15.0 h
20 May 1940
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 | 3.8 °C | +2.5 °C | 104 mm | +1 mm |
| Feb | 5.0 °C | +1.7 °C | 42 mm | -58 mm |
| Mar | 10.4 °C | +2.9 °C | 78 mm | -31 mm |
| Apr | 14.8 °C | +3.7 °C | 103 mm | -23 mm |
| May | 16.5 °C | +1.0 °C | 189 mm | +35 mm |
| Jun | 24.2 °C | +5.0 °C | 86 mm | -82 mm |
| Jul | 21.1 °C | -0.1 °C | 255 mm | +86 mm |
| Aug | 23.2 °C | +2.5 °C | 199 mm | +33 mm |
| Sep | 17.3 °C | -0.1 °C | 200 mm | +75 mm |
| Oct | 12.1 °C | -0.3 °C | 111 mm | +10 mm |
| Nov | 7.1 °C | +1.1 °C | 119 mm | +7 mm |
| Dec | 4.1 °C | +1.9 °C | 27 mm | -82 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 Willisau?
Willisau has a warm-summer humid continental climate (Köppen Dfb). Over 1940-2025, the average annual temperature is 7.6 °C and it receives 1,543 mm of precipitation per year.
What is the hottest day ever recorded in Willisau?
The hottest day measured in Willisau between 1940 and 2025 was 7 July 2015, reaching 33.9 °C.
What is the coldest day in Willisau?
The coldest day measured in Willisau between 1940 and 2025 was 23 January 1942, at -23.3 °C.
Does it snow in Willisau?
Yes. Willisau gets on average 229.0 cm of snow per year and has around 111 frost days.
Has the climate of Willisau warmed?
Yes: Willisau warmed by +2.8 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Willisau?
The wettest day measured in Willisau between 1940 and 2025 was 27 September 1942, with 77 mm of rain in 24 hours.
What was the windiest day in Willisau?
The windiest day measured in Willisau between 1940 and 2025 was 26 December 1999, with winds reaching 35.0 km/h.
What is the warmest month in Willisau?
The warmest month in Willisau is July (16.6 °C on average); the coldest is January (-1.5 °C).
How much does it rain in Willisau?
Willisau receives on average 1,543 mm of precipitation per year, spread over about 187 rainy days.
Is it sunny in Willisau?
Willisau gets on average 8.7 hours of sunshine per day, roughly 3,175 hours per year over 1940-2025.
What is the biggest single-day snowfall in Willisau?
The heaviest 24-hour snowfall measured in Willisau between 1940 and 2025 was 9 February 1999, with 23.6 cm.
Are there tropical nights in Willisau?
Almost never: tropical nights (temperature staying above 20 °C) are virtually non-existent in Willisau.
What was the most extreme apparent temperature in Willisau?
In Willisau, between 1940 and 2025, the highest apparent temperature reached 36.4 °C on 26 June 2019, and the lowest was -29.1 °C on 10 February 1956.
Compare Willisau with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Willisau