Siuntio climate — normals and trends
Siuntio (Finland) has a warm-summer humid continental climate (Dfb) under the Köppen-Geiger classification. Its mean annual temperature is 5.1 °C and it receives 667 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 (17.1 °C on average) and the coldest is February (-5.9 °C). Rainfall peaks in August.
Siuntio averages 144 frost days, 0 hot days (≥ 30 °C) and 131 rainy days per year.
Siuntio has warmed by +2.5 °C between 1940 and 2025, or +0.29 °C per decade. This trend is statistically significant.
The number of frost days there went from about 165 to 123 per year over the period.
The hottest day of the period reached 31.5 °C (on 28 July 2019) and the coldest -36.4 °C (on 10 January 1987).
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
SiuntioUusimaa
- coords
- 60.14°, 24.23°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
5.1°C
Average daily high
7.9°C
Average daily low
2.0°C
Annual rainfall
667mm
Sunshine / day
7.5h
Mean relative humidity
81%
Average peak wind
18.5km/h
Seasonal range
23.0°C
Frost days (< 0 °C)
144 d/yr
Hot days (≥ 30 °C)
0 d/yr
Rainy days (≥ 1 mm)
131 d/yr
Annual snowfall
133.6 cm
Average feels-like high
4.7 °C
Average feels-like low
-1.6 °C
Average peak gust
37.5 km/h
Tropical nights (≥ 20 °C)
0 d/yr
Solar radiation
9.7 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.5 °C
since 1940
+0.3 °C per decade · r² = 0.39 · 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
31.5 °C
28 July 2019
Coldest day
-36.4 °C
10 January 1987
Wettest day
84 mm
12 August 1972
Windiest day
54.8 km/h
23 January 1995
Strongest gust
110.2 km/h
23 January 1995
Hottest feels-like
32.7 °C
28 July 2019
Coldest feels-like
-43.2 °C
10 January 1987
Snowiest day
16.6 cm
16 February 1999
Sunniest day
17.8 h
22 June 2024
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 | 1.3 °C | +4.6 °C | 71 mm | +18 mm |
| Feb | -0.7 °C | +2.8 °C | 20 mm | -22 mm |
| Mar | 5.2 °C | +4.9 °C | 12 mm | -26 mm |
| Apr | 9.2 °C | +2.9 °C | 45 mm | +6 mm |
| May | 13.0 °C | -0.1 °C | 36 mm | -5 mm |
| Jun | 17.1 °C | -0.8 °C | 102 mm | +48 mm |
| Jul | 23.3 °C | +2.8 °C | 85 mm | +13 mm |
| Aug | 18.9 °C | -0.3 °C | 66 mm | -13 mm |
| Sep | 16.8 °C | +2.7 °C | 94 mm | +29 mm |
| Oct | 9.3 °C | +1.2 °C | 56 mm | -3 mm |
| Nov | 6.0 °C | +3.3 °C | 40 mm | -23 mm |
| Dec | 3.7 °C | +4.4 °C | 59 mm | -3 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 Siuntio?
Siuntio has a warm-summer humid continental climate (Köppen Dfb). Over 1940-2025, the average annual temperature is 5.1 °C and it receives 667 mm of precipitation per year.
What is the hottest day ever recorded in Siuntio?
The hottest day measured in Siuntio between 1940 and 2025 was 28 July 2019, reaching 31.5 °C.
What is the coldest day in Siuntio?
The coldest day measured in Siuntio between 1940 and 2025 was 10 January 1987, at -36.4 °C.
Does it snow in Siuntio?
Yes. Siuntio gets on average 133.6 cm of snow per year and has around 144 frost days.
Has the climate of Siuntio warmed?
Yes: Siuntio warmed by +2.5 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Siuntio?
The wettest day measured in Siuntio between 1940 and 2025 was 12 August 1972, with 84 mm of rain in 24 hours.
What was the windiest day in Siuntio?
The windiest day measured in Siuntio between 1940 and 2025 was 23 January 1995, with winds reaching 54.8 km/h.
What is the warmest month in Siuntio?
The warmest month in Siuntio is July (17.1 °C on average); the coldest is February (-5.9 °C).
How much does it rain in Siuntio?
Siuntio receives on average 667 mm of precipitation per year, spread over about 131 rainy days.
Is it sunny in Siuntio?
Siuntio gets on average 7.5 hours of sunshine per day, roughly 2,738 hours per year over 1940-2025.
What is the biggest single-day snowfall in Siuntio?
The heaviest 24-hour snowfall measured in Siuntio between 1940 and 2025 was 16 February 1999, with 16.6 cm.
Are there tropical nights in Siuntio?
Almost never: tropical nights (temperature staying above 20 °C) are virtually non-existent in Siuntio.
What was the most extreme apparent temperature in Siuntio?
In Siuntio, between 1940 and 2025, the highest apparent temperature reached 32.7 °C on 28 July 2019, and the lowest was -43.2 °C on 10 January 1987.
Compare Siuntio with another city
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Nearby cities
The climate around Siuntio