Climate Insights for Semnan

The climate in Semnan is temperate. The average annual temperature is 15°C and approximately 216mm of precipitation falls per year. April is the wettest month, receiving around 40mm of rainfall. Semnan is in the Northern Hemisphere. Summer begins at the end of June and lasts through September. The summer months are: July, August, June. The coldest months are January, February, December, when temperatures can drop to -2°C. Light snow can occur between January and December.

Semnan has a wide annual temperature range, spanning 36°C from the coldest to warmest months. The warmest month is July, when average highs reach 34°C and the mean temperature sits around 28°C. The coldest month is January, when overnight lows fall to -2°C and the daily average is 2°C. On average, daily temperatures fluctuate by about 10°C between overnight lows and afternoon highs. The sharpest temperature change occurs between October and November, with a 8°C shift in average temperatures.

Semnan is a quite dry location, receiving approximately 216mm of precipitation annually, which averages out to around 18mm per month. The wettest month is April, averaging 40mm of rainfall. February and November also tend to see above-average precipitation. The driest month is August, with just 1mm. That's 39mm less than April, the wettest month. Rainfall is heavily concentrated in certain months, creating a distinct wet and dry season. Visitors should plan around these patterns, as the difference between peak and low months is dramatic. Light snowfall can occur between January and December, totalling around 40cm annually. February is the snowiest month with approximately 11cm.

Semnan is relatively calm, with an average annual wind speed of 3km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is July, averaging 3km/h, though still comfortable for most outdoor activities. The calmest conditions occur in November, with average winds dropping to 2km/h, making it an ideal period for wind-sensitive activities. There is moderate seasonal variation in wind speed, with a 1km/h gap between the calmest and windiest months.

It is currently summer in Semnan, which began on June 21, 2026. Semnan is in the Northern Hemisphere, where spring begins in March, summer in June, autumn in September, and winter in December. The warmest period peaks in July at around 34°C, while the coldest stretch bottoms out in January near -2°C. Autumn is next, beginning on September 23, 2026 — 91 days from now.

The best time to visit Semnan is during May, September and October, when the weather is most comfortable for travellers. During these months, average temperatures hover around 19°C with modest rainfall averaging 14mm per month. By contrast, July can be uncomfortably hot with highs reaching 34°C, while January is the coldest period with lows dropping to -2°C. With minimal rainfall expected, you can pack light and plan outdoor activities with confidence.

The table below shows monthly climate averages for Semnan based on historical weather data. Min and max temperatures represent typical overnight lows and afternoon highs for each month, shown in degrees Celsius (°C). Precipitation is measured in millimetres (mm) and indicates the average total rainfall per month. Snow is measured in centimetres (cm) and reflects average monthly snowfall accumulation. Wind speed is the average sustained speed in kilometres per hour (km/h). All values are based on averages from over 10 years of historical weather data. The current month is highlighted for quick reference.