Sejny climate — normals and trends
Sejny (Poland) has a warm-summer humid continental climate (Dfb) under the Köppen-Geiger classification. Its mean annual temperature is 7.0 °C and it receives 636 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 (17.9 °C on average) and the coldest is January (-4.3 °C). Rainfall peaks in July.
Sejny averages 117 frost days, 2 hot days (≥ 30 °C) and 134 rainy days per year.
Sejny has warmed by +2.6 °C between 1940 and 2025, or +0.30 °C per decade. This trend is statistically significant.
The number of frost days there went from about 138 to 96 per year over the period.
The hottest day of the period reached 36.0 °C (on 8 August 2015) and the coldest -33.4 °C (on 11 January 1950).
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
SejnyPodlasie
- coords
- 54.11°, 23.35°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
7.0°C
Average daily high
10.4°C
Average daily low
3.5°C
Annual rainfall
636mm
Sunshine / day
7.0h
Mean relative humidity
80%
Average peak wind
18.7km/h
Seasonal range
22.2°C
Frost days (< 0 °C)
117 d/yr
Hot days (≥ 30 °C)
2 d/yr
Rainy days (≥ 1 mm)
134 d/yr
Annual snowfall
77.7 cm
Average feels-like high
7.4 °C
Average feels-like low
0.2 °C
Average peak gust
36.0 km/h
Tropical nights (≥ 20 °C)
0 d/yr
Solar radiation
10.1 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.6 °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
36.0 °C
8 August 2015
Coldest day
-33.4 °C
11 January 1950
Wettest day
71 mm
5 August 1966
Windiest day
57.3 km/h
22 February 1953
Strongest gust
101.9 km/h
7 March 1983
Hottest feels-like
36.2 °C
17 July 2007
Coldest feels-like
-38.7 °C
11 January 1950
Snowiest day
13.9 cm
4 April 1960
Sunniest day
16.7 h
21 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 | 3.4 °C | +5.7 °C | 36 mm | -4 mm |
| Feb | 0.5 °C | +1.6 °C | 21 mm | -14 mm |
| Mar | 10.2 °C | +6.6 °C | 36 mm | -0 mm |
| Apr | 15.5 °C | +4.5 °C | 16 mm | -31 mm |
| May | 15.3 °C | -1.7 °C | 49 mm | -12 mm |
| Jun | 21.2 °C | +0.7 °C | 57 mm | -15 mm |
| Jul | 23.5 °C | +1.3 °C | 142 mm | +58 mm |
| Aug | 22.0 °C | +0.3 °C | 48 mm | -23 mm |
| Sep | 19.7 °C | +2.9 °C | 65 mm | +11 mm |
| Oct | 10.9 °C | +0.3 °C | 82 mm | +35 mm |
| Nov | 4.9 °C | +0.8 °C | 60 mm | +14 mm |
| Dec | 3.5 °C | +3.4 °C | 22 mm | -22 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 Sejny?
Sejny has a warm-summer humid continental climate (Köppen Dfb). Over 1940-2025, the average annual temperature is 7.0 °C and it receives 636 mm of precipitation per year.
What is the hottest day ever recorded in Sejny?
The hottest day measured in Sejny between 1940 and 2025 was 8 August 2015, reaching 36.0 °C.
What is the coldest day in Sejny?
The coldest day measured in Sejny between 1940 and 2025 was 11 January 1950, at -33.4 °C.
Does it snow in Sejny?
Yes. Sejny gets on average 77.7 cm of snow per year and has around 117 frost days.
Has the climate of Sejny warmed?
Yes: Sejny warmed by +2.6 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Sejny?
The wettest day measured in Sejny between 1940 and 2025 was 5 August 1966, with 71 mm of rain in 24 hours.
What was the windiest day in Sejny?
The windiest day measured in Sejny between 1940 and 2025 was 22 February 1953, with winds reaching 57.3 km/h.
What is the warmest month in Sejny?
The warmest month in Sejny is July (17.9 °C on average); the coldest is January (-4.3 °C).
How much does it rain in Sejny?
Sejny receives on average 636 mm of precipitation per year, spread over about 134 rainy days.
Is it sunny in Sejny?
Sejny gets on average 7.0 hours of sunshine per day, roughly 2,555 hours per year over 1940-2025.
What is the biggest single-day snowfall in Sejny?
The heaviest 24-hour snowfall measured in Sejny between 1940 and 2025 was 4 April 1960, with 13.9 cm.
Are there tropical nights in Sejny?
Almost never: tropical nights (temperature staying above 20 °C) are virtually non-existent in Sejny.
What was the most extreme apparent temperature in Sejny?
In Sejny, between 1940 and 2025, the highest apparent temperature reached 36.2 °C on 17 July 2007, and the lowest was -38.7 °C on 11 January 1950.
Compare Sejny with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Sejny