Climate Insights for Gilroy

The climate in Gilroy is temperate. The average annual temperature is 15°C and approximately 418mm of precipitation falls per year. January is the wettest month, receiving around 106mm of rainfall. Gilroy is in the Northern Hemisphere. Summer begins at the end of June and lasts through September. The summer months are: August, July, September. The coldest months are December, February, January, when temperatures can drop to 5°C.

Temperatures in Gilroy vary considerably across the year, with a 22°C difference between the coldest and warmest months. The warmest month is August, when average highs reach 27°C and the mean temperature sits around 20°C. December is the coolest month, with minimum temperatures around 5°C and an average of 10°C. On average, daily temperatures fluctuate by about 11°C between overnight lows and afternoon highs. The sharpest temperature change occurs between October and November, with a 5°C shift in average temperatures.

Gilroy is a relatively dry area, receiving approximately 418mm of precipitation annually, which averages out to around 35mm per month. The wettest month is January, averaging 106mm of rainfall. December and March also tend to see above-average precipitation. The driest month is August, with just 0mm. That's 105mm 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.

Gilroy is relatively calm, with an average annual wind speed of 11km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is May, averaging 14km/h, though still comfortable for most outdoor activities. The calmest conditions occur in November, with average winds dropping to 9km/h, making it an ideal period for wind-sensitive activities. There is moderate seasonal variation in wind speed, with a 5km/h gap between the calmest and windiest months.

It is currently spring in Gilroy, which began on March 20, 2026. Gilroy 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 August at around 27°C, while the coldest stretch bottoms out in December near 5°C. Summer is next, beginning on June 21, 2026 — 84 days from now.

The best time to visit Gilroy is during May, June, July, August, September and October, when the weather is most comfortable for travellers. During these months, average temperatures hover around 18°C with modest rainfall averaging 6mm 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 Gilroy 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.