Climate Insights for Vallejo

The climate in Vallejo is temperate. The average annual temperature is 16°C and approximately 637mm of precipitation falls per year. March is the wettest month, receiving around 165mm of rainfall. Vallejo is in the Northern Hemisphere. Summer begins at the end of June and lasts through September. The summer months are: June, September, July. The coldest months are December, February, January, when temperatures can drop to 5°C.

Temperatures in Vallejo vary considerably across the year, with a 25°C difference between the coldest and warmest months. The warmest month is June, when average highs reach 30°C and the mean temperature sits around 21°C. December is the coolest month, with minimum temperatures around 5°C and an average of 9°C. On average, daily temperatures fluctuate by about 12°C between overnight lows and afternoon highs. The sharpest temperature change occurs between November and December, with a 4°C shift in average temperatures.

Vallejo is a relatively dry area, receiving approximately 637mm of precipitation annually, which averages out to around 53mm per month. The wettest month is March, averaging 165mm of rainfall. January and October also tend to see above-average precipitation. The driest month is September, with just 0mm. That's 164mm less than March, 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.

Vallejo is relatively calm, with an average annual wind speed of 2km/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 Vallejo, which began on June 21, 2026. Vallejo 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 June at around 30°C, while the coldest stretch bottoms out in December near 5°C. Autumn is next, beginning on September 23, 2026 — 53 days from now.

The best time to visit Vallejo is during April, May, June, July, August, September and October, when the weather is most comfortable for travellers. During these months, average temperatures hover around 19°C with modest rainfall averaging 23mm per month. By contrast, December can be quite cold with temperatures dropping to 5°C. With minimal rainfall expected, you can pack light and plan outdoor activities with confidence.

The table below shows monthly climate averages for Vallejo 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.