Fairfax Weather & Climate: Best Time to Visit
Average temperatures, rainfall, sunshine and the best time to visit Fairfax.
Climate overview of Fairfax
Temperatures in Fairfax, Marin County, United States of America, vary greatly throughout the year. July is the hottest month at 28°C (82°F), while December is the coldest at 13°C (55°F).
Fairfax sees a moderate amount of rainfall, totalling around 868 mm (34 in) per year. It experiences a distinct dry season from May to September, with warm summers and mild winters, creating some seasonal variation. Sunshine peaks in May, when the city sees around 10.8 hours of sunshine per day.
Fairfax Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in Fairfax - and find the best time to visit.
Monthly Temperature in Fairfax
The climate in Fairfax is known for significant temperature differences throughout the year, making the weather dynamic. Average maximum daytime temperatures range from a comfortable 28°C (82°F) in July, the warmest time of the year, to a moderate 13°C (55°F) during cooler months like December.
At night, you can expect temperatures ranging from 12°C (54°F) in July to around 5°C (41°F) during December.
Check out our detailed temperature page for more information.
Temperature ranges by month
Rainfall in Fairfax
Generally, Fairfax receives mid-range precipitation levels, with 868 mm (34 in) annually. Significant seasonal changes in precipitation occur throughout the year. In the wettest month, December it receives heavy rainfall, averaging 190 mm (7.5 in) of precipitation, recorded across 13 rainy days. In contrast, the driest month August brings less rainfall, with 0 mm (0 in) over 0 rainy days. For more details, please visit our Fairfax Precipitation page.
The mean monthly precipitation over the year, including rain, hail, and snow
The average number of days each month with precipitation
Sunshine Hours in Fairfax
Seasonal changes in sunshine hours are quite dramatic in Fairfax. While May receives considerable daily sunshine with up to 10.8 hours, December marks the darkest time of the year, where sunshine is scarce with only 5.3 hours of sunlight per day.
Visit our detailed sunshine hours page for more information.
Monthly hours of sunshine
Daily hours of sunshine
Daily percentage of sunshine
Humidity in Fairfax by Month
The relative humidity is high throughout the year in Fairfax.
The city experiences its highest humidity in January, reaching 80%. In June, the humidity drops to its lowest level at 71%. What does this mean? Read our detailed page on humidity levels for further details.
Relative humidity over the year
Best Time to Visit Fairfax
Monthly ratings reflect general weather comfort, based on daytime temperature and rainfall. Swimming and winter conditions are highlighted separately where relevant.
- Best overall: April, May, June, July, August, September and October
- Warmest weather: July, August and September
- Most sunshine: April, May, June and July
- Fewest rainy days: June, July, August and September
- Wettest months: January, February, March, November and December, when rainfall is highest.
- Seasonal pattern: A distinct dry season from May to September, with warm summers and mild winters
Frequently asked questions about the climate in Fairfax
What is the best time to visit Fairfax?
April, May, June, July, August, September and October typically offer the most optimal weather in Fairfax. In contrast, December tends to have less optimal conditions. Fairfax has a distinct dry season from May to September, with warm summers and mild winters.
What temperatures can I expect in Fairfax?
Daytime highs range from 13°C (55°F) in December to 28°C (82°F) in July. Nighttime lows range from 5°C (41°F) to 12°C (54°F). Temperatures vary considerably through the year.
How much rain does Fairfax get?
Annual rainfall is around 868 mm (34 in). December is the wettest month with 190 mm (7.5 in), while August is the driest with 0 mm (0 in).
How sunny is Fairfax?
Fairfax receives around 3,058 hours of sunshine per year. May is the sunniest month with 324 hours, while December is the cloudiest with just 160 hours. Overall, Fairfax enjoys abundant sunshine.
Fairfax 3-Day Forecast
Fairfax 3-Day Forecast
Fairfax on the map
Fairfax is highlighted - select any city to see its climate.
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