Climate Overview
The climate in San Francisco is hot. The average annual temperature is 27°C and approximately 1396mm of precipitation falls per year. September is the wettest month, receiving around 232mm of rainfall. San Francisco is in the Northern Hemisphere. Summer begins at the end of June and lasts through September. The summer months are: May, April, March. The coldest months are January, February, December, when temperatures can drop to 19°C.
Temperature
San Francisco sees moderate temperature variation throughout the year, ranging from 19°C to 39°C. May is the hottest month, with daytime highs reaching 39°C and an average of 31°C. January is the coolest month, with minimum temperatures around 19°C and an average of 24°C. On average, daily temperatures fluctuate by about 11°C between overnight lows and afternoon highs. The sharpest temperature change occurs between February and March, with a 3°C shift in average temperatures.
Precipitation
San Francisco is a fairly wet location, receiving approximately 1396mm of precipitation annually, which averages out to around 116mm per month. The wettest month is September, averaging 232mm of rainfall. June and October also tend to see above-average precipitation. The driest month is March, with just 29mm. That's 203mm less than September, 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.
Wind
San Francisco is relatively calm, with an average annual wind speed of 6km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is April, averaging 8km/h, though still comfortable for most outdoor activities. The calmest conditions occur in September, with average winds dropping to 4km/h, making it an ideal period for wind-sensitive activities. There is moderate seasonal variation in wind speed, with a 4km/h gap between the calmest and windiest months.
Seasons
87 days until Winter
It is currently autumn in San Francisco, which began on September 23, 2026. San Francisco 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 May at around 39°C, while the coldest stretch bottoms out in January near 19°C. Winter is next, beginning on December 21, 2026 (87 days from now).
Spring
Temperatures range from 22 to 39°C. Rainfall is relatively light, with around 140mm over the season and a monthly average of 47mm. Winds are generally light, averaging 8km/h. Light layers work well as temperatures warm through the season. It is a great time to be outdoors.
Summer
Temperatures range from 24 to 35°C. Rainfall is heavy, totalling around 544mm across the season with a monthly average of 181mm. Winds are generally light, averaging 5km/h. Light, breathable clothing is ideal. Perfect conditions for outdoor activities.
Autumn
Temperatures range from 21 to 33°C. Rainfall is heavy, totalling around 549mm across the season with a monthly average of 183mm. Winds are generally light, averaging 5km/h. A waterproof jacket and sturdy footwear are recommended as rain becomes more frequent.
Winter
Temperatures range from 19 to 31°C. Precipitation is moderate at around 164mm for the season, averaging 55mm per month. Winds are generally light, averaging 6km/h. A light jacket or sweater is usually sufficient, though cooler evenings may call for an extra layer.
Best Time to Visit
The best time to visit San Francisco is during January and December, when the weather is most comfortable for travellers. During these months, average temperatures hover around 24°C with modest rainfall averaging 65mm per month. By contrast, May can be uncomfortably hot with temperatures reaching 39°C. A light rain jacket is recommended, though showers are generally brief and shouldn't disrupt your plans.
Monthly Climate Data
The table below shows monthly climate averages for San Francisco 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. 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.
