Climate Insights for Guerneville

The climate in Guerneville is temperate. The average annual temperature is 14°C and approximately 742mm of precipitation falls per year. January is the wettest month, receiving around 187mm of rainfall. Guerneville is in the Northern Hemisphere. Summer begins at the end of June and lasts through September. The summer months are: September, August, July. The coldest months are December, February, January, when temperatures can drop to 7°C.

Guerneville sees moderate temperature variation throughout the year, ranging from 7°C to 22°C. September is the warmest month, though highs remain moderate at 22°C with a mean of 17°C. December is the coolest month, with minimum temperatures around 7°C and an average of 10°C. Daily temperature variation is modest, with an average difference of 7°C between highs and lows. The sharpest temperature change occurs between October and November, with a 3°C shift in average temperatures.

Guerneville is a relatively dry area, receiving approximately 742mm of precipitation annually, which averages out to around 62mm per month. The wettest month is January, averaging 187mm of rainfall. February and March also tend to see above-average precipitation. The driest month is July, with just 1mm. That's 187mm less than January, 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.

Guerneville is relatively calm, with an average annual wind speed of 4km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is June, averaging 5km/h, though still comfortable for most outdoor activities. The calmest conditions occur in November, with average winds dropping to 3km/h, making it an ideal period for wind-sensitive activities. There is moderate seasonal variation in wind speed, with a 2km/h gap between the calmest and windiest months.

It is currently spring in Guerneville, which began on March 20, 2026. Guerneville 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 September at around 22°C, while the coldest stretch bottoms out in December near 7°C. Summer is next, beginning on June 21, 2026 — 7 days from now.

The best time to visit Guerneville is during June, July, August, September and October, when the weather is most comfortable for travellers. During these months, average temperatures hover around 16°C with modest rainfall averaging 9mm per month. By contrast, December can be quite cold with temperatures dropping to 7°C. With minimal rainfall expected, you can pack light and plan outdoor activities with confidence.

The table below shows monthly climate averages for Guerneville 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.