Fairfield (CA) Temperature by Month

The average annual maximum temperature in Fairfield, California, United States of America is 23°C (73°F), with daytime highs ranging from 14°C (57°F) in December to 31°C (88°F) in July. This page covers monthly averages, day-night differences, and how Fairfield compares to cities worldwide.

Visitors to Fairfield will encounter a climate influenced by big temperature differences across the year. Nighttime temperatures range from 14°C (57°F) in July to 3°C (37°F) in December.

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

The coldest point of the day usually falls between 4 AM and 6 AM, with temperatures peaking around 3 PM. July, the city's warmest month, gets 440 hours of sunshine.

The chart below shows the average temperature throughout the year:

Fairfield's average annual maximum temperature is 23°C (73°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.

Queenstown, New Zealand averages 10°C (50°F) annually, remember seasons are flipped, so its coldest months fall in June and July.

Shanghai, China averages 21°C (70°F) a year, with warm summers, mild winters, and a noticeable spring and autumn.

Melbourne, Australia averages 20°C (68°F) annually, known for unpredictable weather, with four seasons sometimes happening in one day.

Temperature alone doesn't tell the whole story, humidity plays a big role in how warm or cold it actually feels. High humidity in summer makes the heat feel more intense, particularly once temperatures climb above 25°C. In winter, the same humidity can make cold air feel sharper than the thermometer suggests.

In Fairfield, December is the coolest month, with average highs of 14°C (57°F) and humidity around 83%, considered very high. In July, the warmest month, temperatures average 31°C (88°F) with 53% humidity, conditions that feel moderate. For a full picture, see our humidity page.

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 Fairfield this rarely lasts long on the ground.

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