Mill Valley (CA) Weather & Climate: Best Time to Visit
Average temperatures, rainfall, sunshine and the best time to visit Mill Valley.
Climate overview of Mill Valley
Mill Valley, California, United States of America, has a moderate seasonal temperature range, with September reaching 24°C (75°F) and December cooling to 14°C (57°F).
Mill Valley sees a moderate amount of rainfall, totalling around 774 mm (30 in) per year. It experiences a distinct dry season from May to September, with warm summers and mild winters, creating some seasonal variation. The sunniest month is May, with 10.8 hours of sunshine per day on average.
Mill Valley Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in Mill Valley - and find the best time to visit.
Monthly Temperature in Mill Valley
In Mill Valley, seasonal changes bring about a moderate variation in temperatures. Average maximum daytime temperatures range from a comfortable 24°C (75°F) in September, the warmest time of the year, to a moderate 14°C (57°F) during cooler months like December.
At night, you can expect temperatures ranging from 12°C (54°F) in September to around 6°C (43°F) during December.
Check out our detailed temperature page for more information.
Temperature ranges by month
Rainfall in Mill Valley
Generally, Mill Valley experiences moderate precipitation patterns, averaging 774 mm (30 in) yearly. Significant seasonal changes in precipitation occur throughout the year. In the wettest month, December it receives heavy rainfall, averaging 172 mm (6.8 in) of precipitation, recorded across 13 rainy days. In contrast, the driest month July brings less rainfall, with 0.3 mm (0.01 in) over 0 rainy days. For more details, please visit our Mill Valley 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 Mill Valley
Seasonal changes in sunshine hours are quite dramatic in Mill Valley. 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 Mill Valley by Month
The relative humidity is high throughout the year in Mill Valley.
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 Mill Valley
Each month is rated for comfortable sightseeing weather — mild temperatures and low rainfall. Tap a month for its full averages; your ideal time may differ for a beach or winter trip (see below).
- Best overall: May, June, July, August, September and October
- Warmest weather: June, July, August and September
- Most sunshine: April, May, June and July
- Fewest rainy days: June, July, August and September
- Wettest period: January, February, March, November and December, when rainfall peaks.
- Climate seasons: a distinct dry season from May to September, with warm summers and mild winters
Frequently asked questions about the climate in Mill Valley
What is the best time to visit Mill Valley?
May, June, July, August, September and October typically offer the most optimal weather in Mill Valley. In contrast, January, February and December tend to have less optimal conditions. Mill Valley has a distinct dry season from May to September, with warm summers and mild winters.
What temperatures can I expect in Mill Valley?
Daytime highs range from 14°C (57°F) in December to 24°C (75°F) in September. Nighttime lows range from 6°C (43°F) to 12°C (54°F).
How much rain does Mill Valley get?
Annual rainfall is around 774 mm (30 in). December is the wettest month with 172 mm (6.8 in), while July is the driest with 0.3 mm (0.01 in).
How sunny is Mill Valley?
Mill Valley 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, Mill Valley enjoys abundant sunshine.
Mill Valley 3-Day Forecast
Mill Valley (CA) 3-Day Forecast
Mill Valley on the map
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