Semnan climate — normals and trends
Semnan (Iran) has a cold desert climate (BWk) under the Köppen-Geiger classification. Its mean annual temperature is 15.8 °C and it receives 99 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 (29.2 °C on average) and the coldest is January (2.1 °C). Rainfall peaks in March.
Semnan averages 61 frost days, 107 hot days (≥ 30 °C) and 24 rainy days per year.
Semnan has warmed by +3.0 °C between 1940 and 2025, or +0.35 °C per decade. This trend is statistically significant.
The number of frost days there went from about 84 to 38 per year over the period.
The hottest day of the period reached 42.7 °C (on 1 July 2025) and the coldest -17.2 °C (on 20 January 1964).
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
SemnanSemnan Province
- coords
- 35.58°, 53.39°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
15.8°C
Average daily high
21.3°C
Average daily low
10.2°C
Annual rainfall
99mm
Sunshine / day
11.0h
Mean relative humidity
43%
Average peak wind
16.6km/h
Seasonal range
27.1°C
Frost days (< 0 °C)
61 d/yr
Hot days (≥ 30 °C)
107 d/yr
Rainy days (≥ 1 mm)
24 d/yr
Annual snowfall
14.9 cm
Average feels-like high
18.4 °C
Average feels-like low
7.2 °C
Average peak gust
32.4 km/h
Tropical nights (≥ 20 °C)
71 d/yr
Solar radiation
19.7 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+3.0 °C
since 1940
+0.4 °C per decade · r² = 0.54 · 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
42.7 °C
1 July 2025
Coldest day
-17.2 °C
20 January 1964
Wettest day
33 mm
11 February 1980
Windiest day
49.5 km/h
12 May 1958
Strongest gust
88.6 km/h
12 May 1958
Hottest feels-like
39.8 °C
9 July 1989
Coldest feels-like
-22.7 °C
20 January 1964
Snowiest day
12.3 cm
3 February 1968
Sunniest day
13.3 h
17 June 1946
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 | 9.9 °C | +3.1 °C | 5 mm | -9 mm |
| Feb | 9.2 °C | +0.1 °C | 6 mm | -9 mm |
| Mar | 17.5 °C | +3.1 °C | 15 mm | -5 mm |
| Apr | 26.2 °C | +5.1 °C | 4 mm | -9 mm |
| May | 31.9 °C | +4.7 °C | 1 mm | -6 mm |
| Jun | 33.4 °C | +0.6 °C | 1 mm | 0 mm |
| Jul | 37.2 °C | +1.8 °C | 1 mm | -0 mm |
| Aug | 36.3 °C | +2.4 °C | 0 mm | -1 mm |
| Sep | 31.4 °C | +1.7 °C | 1 mm | -1 mm |
| Oct | 26.1 °C | +3.6 °C | 0 mm | -4 mm |
| Nov | 18.3 °C | +4.1 °C | 0 mm | -10 mm |
| Dec | 10.2 °C | +1.8 °C | 6 mm | -7 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 Semnan?
Semnan has a cold desert climate (Köppen BWk). Over 1940-2025, the average annual temperature is 15.8 °C and it receives 99 mm of precipitation per year.
What is the hottest day ever recorded in Semnan?
The hottest day measured in Semnan between 1940 and 2025 was 1 July 2025, reaching 42.7 °C.
What is the coldest day in Semnan?
The coldest day measured in Semnan between 1940 and 2025 was 20 January 1964, at -17.2 °C.
Does it snow in Semnan?
Yes. Semnan gets on average 14.9 cm of snow per year and has around 61 frost days.
Has the climate of Semnan warmed?
Yes: Semnan warmed by +3.0 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Semnan?
The wettest day measured in Semnan between 1940 and 2025 was 11 February 1980, with 33 mm of rain in 24 hours.
What was the windiest day in Semnan?
The windiest day measured in Semnan between 1940 and 2025 was 12 May 1958, with winds reaching 49.5 km/h.
What is the warmest month in Semnan?
The warmest month in Semnan is July (29.2 °C on average); the coldest is January (2.1 °C).
How much does it rain in Semnan?
Semnan receives on average 99 mm of precipitation per year, spread over about 24 rainy days.
Is it sunny in Semnan?
Semnan gets on average 11.0 hours of sunshine per day, roughly 4,015 hours per year over 1940-2025.
What is the biggest single-day snowfall in Semnan?
The heaviest 24-hour snowfall measured in Semnan between 1940 and 2025 was 3 February 1968, with 12.3 cm.
Are there tropical nights in Semnan?
Yes: Semnan has on average 71 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Semnan?
In Semnan, between 1940 and 2025, the highest apparent temperature reached 39.8 °C on 9 July 1989, and the lowest was -22.7 °C on 20 January 1964.
Compare Semnan with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Semnan