Climate Insights for Grass Valley

The climate in Grass Valley is temperate. The average annual temperature is 15°C and approximately 1491mm of precipitation falls per year. January is the wettest month, receiving around 276mm of rainfall. Grass Valley 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 December, February, January, when temperatures can drop to 3°C. Snowfall occurs from January to December, with around 116cm accumulating over the season.

Temperatures in Grass Valley vary considerably across the year, with a 31°C difference between the coldest and warmest months. The warmest month is July, when average highs reach 34°C and the mean temperature sits around 26°C. December is the coolest month, with minimum temperatures around 3°C and an average of 7°C. On average, daily temperatures fluctuate by about 13°C between overnight lows and afternoon highs. The sharpest temperature change occurs between October and November, with a 6°C shift in average temperatures.

Grass Valley is a fairly wet location, receiving approximately 1491mm of precipitation annually, which averages out to around 124mm per month. The wettest month is January, averaging 276mm of rainfall. December and March also tend to see above-average precipitation. The driest month is July, with just 1mm. That's 274mm 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. Snowfall is a regular feature from January to December, with around 116cm accumulating over the season. March typically sees the most snow at around 33cm.

Grass Valley is mildly breezy, with an average annual wind speed of 14km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is February, averaging 16km/h, though still comfortable for most outdoor activities. The calmest conditions occur in August, with average winds dropping to 12km/h, making it an ideal period for wind-sensitive activities. Wind conditions are fairly consistent throughout the year, varying by only 4km/h between the calmest and windiest months. Wind tends to be stronger during winter months, driven by seasonal pressure systems. The seasonal averages break down to 16km/h in winter, 14km/h in spring, 13km/h in summer, 14km/h in autumn.

It is currently spring in Grass Valley, which began on March 20, 2026. Grass Valley 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 December near 3°C. Summer is next, beginning on June 21, 2026 — 83 days from now.

The best time to visit Grass Valley is during May, June, August, September and October, when the weather is most comfortable for travellers. During these months, average temperatures hover around 20°C with modest rainfall averaging 36mm per month. By contrast, July can be uncomfortably hot with highs reaching 34°C, while December is the coldest period with lows dropping to 3°C. A light rain jacket is recommended, though showers are generally brief and shouldn't disrupt your plans.

The table below shows monthly climate averages for Grass Valley 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.