Grass Valley (CA) Temperature by Month

Grass Valley in California, United States of America sees significant seasonal temperature differences, with daytime highs between 10°C (50°F) in December and 31°C (88°F) in July, averaging 20°C (68°F) annually. Explore the full monthly breakdown below.

Depending on the time of the year, temperatures range from very warm to cold in Grass Valley. Nighttime lows follow the same pattern, ranging from 16°C (61°F) to 1°C (34°F).

The chart below illustrates the average maximum day and minimum night temperatures in Grass Valley by month:

Temperatures tend to bottom out between 4 AM and 6 AM, then climb to their daily peak around 3 PM.

The chart below shows the average temperature throughout the year:

Grass Valley's average annual maximum temperature is 20°C (68°F). To put that in context, here's how it compares to a few well-known destinations:

Rome, Italy averages 20°C (68°F) annually, with reliably warm summers and comfortable winters.

Interlaken, Switzerland averages 8°C (46°F) a year, with cold winters and cool summers thanks to its Alpine setting.

San Francisco, USA averages 19°C (66°F) annually, but with little seasonal variation, summers are often cool and foggy, winters mild.

Tokyo, Japan averages 21°C (70°F) a year, with hot summers, cool winters, and a well-defined cherry blossom spring.

Climate temperature data is typically calculated as a 30-year average. This smooths out year-to-year variability and gives a more reliable picture of what a place is actually like, rather than what happened in any single unusual year.

The readings come from a range of sources, land-based weather stations, ocean buoys, ships, and satellites. That data is collected by weather services around the world, then pooled, quality-checked, and averaged to produce the climate records you see here.

Seasonal temperature shifts influence more than just how warm it feels, they also drive changes in rainfall, cloud cover, and wind patterns throughout the year.

Warmer air holds more moisture, which tends to mean heavier or more frequent rain during the warmer months. When temperatures drop in winter, any precipitation that does fall is more likely to come as snow or sleet, though in Grass Valley this rarely lasts long on the ground.

For more on Grass Valley's weather, including monthly rainfall, sunshine hours, and humidity, visit our Grass Valley climate page.