Semnan climate
Semnan (Iran) has a cold semi-arid climate (Köppen BSk). The average temperature over the year is 16 °C61 °F, and about 234 mm9.2 in of precipitation falls in an average year.
Temperature by month
Precipitation by month
Semnan climate table
| Month | High °C°F | Low °C°F | Mean °C°F | Precip. mmin |
|---|---|---|---|---|
| Jan | 846 | −130 | 338 | 281.1 |
| Feb | 1050 | 032 | 541 | 291.1 |
| Mar | 1661 | 540 | 1051 | 251.0 |
| Apr | 2271 | 949 | 1560 | 230.9 |
| May | 2883 | 1559 | 2271 | 110.4 |
| Jun | 3493 | 1966 | 2780 | 80.3 |
| Jul | 3697 | 2271 | 2984 | 70.3 |
| Aug | 3595 | 2169 | 2882 | 90.3 |
| Sep | 3187 | 1763 | 2475 | 140.6 |
| Oct | 2475 | 1254 | 1864 | 251.0 |
| Nov | 1558 | 540 | 1049 | 301.2 |
| Dec | 949 | 133 | 541 | 241.0 |
| Year | 3697 | −130 | 1661 | 2349.2 |
“Year” row: highest monthly high, lowest monthly low, annual mean and annual total.
| Month | Humid. | Cloud | Solar | Daylight |
|---|---|---|---|---|
| Jan | 65% | 51% | 2.8 | 9:00 |
| Feb | 62% | 52% | 3.7 | 10:51 |
| Mar | 54% | 55% | 4.9 | 11:52 |
| Apr | 52% | 57% | 5.9 | 13:03 |
| May | 43% | 49% | 7.1 | 14:02 |
| Jun | 34% | 35% | 7.9 | 14:33 |
| Jul | 33% | 36% | 7.6 | 14:20 |
| Aug | 34% | 31% | 7.0 | 13:29 |
| Sep | 38% | 29% | 5.9 | 12:21 |
| Oct | 47% | 38% | 4.5 | 11:13 |
| Nov | 60% | 49% | 3.1 | 10:14 |
| Dec | 66% | 49% | 2.5 | 9:46 |
Humid. = average relative humidity at 2 m; cloud = average cloud amount; solar = average daily solar energy reaching the ground in kWh/m² (all-sky); daylight in hours:minutes, calculated for the 15th of each month.
What the climate of Semnan is like
The warmest month is July, with an average high of 36 °C97 °F and a low of 22 °C71 °F. The coldest is January, when highs average 8 °C46 °F and lows −1 °C30 °F. Seasons are strongly marked: the warmest month is on average 25.4 °C45.7 °F warmer than the coldest.
It is dry, with about 234 mm9.2 in of precipitation per year. The wettest three-month stretch is November–January, which brings 35% of the annual total. Months with less than 20 mm0.8 in on average: May–September. The wettest month is November (30 mm1.2 in), the driest is July (7 mm0.3 in).
Relative humidity ranges from 33% in July to 66% in December. The clearest skies (lowest average cloud amount, 29%) are typical of September. Average wind speed near the ground ranges from 7 km/h (4 mph) in December to 15 km/h (9 mph) in July. Daylight lasts from about 9.8 hours in December to 14.5 hours in June.
Best time to visit Semnan
Based on these averages, the most comfortable months for sightseeing and outdoor activities are April and May and October: average highs of 22 °C71 °F to 28 °C83 °F with 11 mm0.4 in to 25 mm1.0 in of precipitation per month.
The most challenging month is January, which is cold, with average highs of 8 °C46 °F.
Comfort score: months are ranked by how close they come to an average high of 21–28 °C (70–82 °F), lows above 5 °C (41 °F), little precipitation and moderate humidity. The best-ranked months of each place are recommended, even where none meets all of these. These are general rules of thumb applied to long-term averages.
What to pack for Semnan
- Winter (December–February) — highs 846 to 10 °C50 °F, lows −130 to 1 °C33 °F, about 27 mm1.1 in of precipitation a month. Pack a warm coat, layers and closed shoes and shoes with good grip, as frost is common.
- Spring (March–May) — highs 1661 to 28 °C83 °F, lows 540 to 15 °C59 °F, about 20 mm0.8 in of precipitation a month. Pack light layers — T-shirts plus a light sweater or jacket and an extra layer for the cooler mornings and evenings.
- Summer (June–August) — highs 3493 to 36 °C97 °F, lows 1966 to 22 °C71 °F, about 8 mm0.3 in of precipitation a month. Pack very light, breathable clothing, a sun hat and plenty of water.
- Autumn (September–November) — highs 1558 to 31 °C87 °F, lows 540 to 17 °C63 °F, about 23 mm0.9 in of precipitation a month. Pack light layers — T-shirts plus a light sweater or jacket and an extra layer for the cooler mornings and evenings.
How Semnan compares
Compared with Qaem Shahr, about 110 km to the northwest, Semnan is on average 3 °C5.4 °F cooler and receives 56% less precipitation (234 mm9.2 in vs 536 mm21 in). The difference is largest in December (5.5 °C9.8 °F cooler).
Of the 82 places in Iran covered by World Climates, Semnan is the 44th warmest by annual mean temperature and the 51st wettest by annual precipitation. See all of them on the Iran climate page.
Places in other countries with the most similar temperature and rainfall pattern: Sumgayit (Azerbaijan, BWk), Manas (Kyrgyzstan, BSk) and Isfara (Tajikistan, BWk).
Nearby places
- Qaem Shahr 110 km · 19 °C67 °F · 536 mm21 in
- Sari 114 km · 19 °C67 °F · 536 mm21 in
- Amol 136 km · 19 °C67 °F · 647 mm25 in
- Qarchak 165 km · 18 °C65 °F · 334 mm13 in
- Gorgan 169 km · 20 °C68 °F · 282 mm11 in
- Shahrud 170 km · 13 °C55 °F · 207 mm8.2 in
- Tehran 179 km · 17 °C62 °F · 311 mm12 in
- Chalus 214 km · 21 °C70 °F · 799 mm31 in
Frequently asked questions
What is the warmest month in Semnan?
July is the warmest month in Semnan, with an average high of 36 °C (97 °F) and an average low of 22 °C (71 °F).
What is the coldest month in Semnan?
January is the coldest month, with an average high of 8 °C (46 °F) and an average low of -1 °C (30 °F).
When does it rain the most in Semnan?
November is the wettest month with about 30 mm (1.2 in) of precipitation; July is the driest with about 7 mm (0.3 in).
What is the best time to visit Semnan?
Judging by long-term averages, the most comfortable months are April and May and October.
About this data
All figures are 25-year averages (January 2001 – December 2025) from the NASA POWER project. Temperature, humidity, wind and precipitation come from the MERRA-2 reanalysis (precipitation is the bias-corrected MERRA-2 product), cloud and solar values from CERES satellite data. They describe a grid cell of roughly 50–70 km, not a single weather station, so they can differ from airport records — most of all on coasts, in mountains and for rainfall. Average highs and lows are the monthly mean temperature plus/minus half of the average daily temperature range. Counts of rainy days are not part of this dataset.
The grid cell’s average elevation is 1,719 m, while Semnan lies at about 1,148 m. Temperatures on this page were therefore adjusted by +3.7 °C6.7 °F using the standard lapse rate of 6.5 °C per 1,000 m.