San Mateo Weather in September

September in San Mateo brings high temperatures, with daytime highs of 24°C (75°F) and nights around 13°C (55°F). Only 3.5 mm (0.1 in) of rainfall is typical, making it a largely dry month.

Rainfall in San Mateo in September

The climate data from previous years indicates about a single day of rain, averaging 3.5 mm (0.1 in) for the month. If rain does fall, it tends to be very light and barely worth getting out an umbrella for.

Temperature in San Mateo in September

September is one of the better months to visit San Mateo. Expect 24°C (75°F) during the day and 13°C (55°F) at night. Conditions stay fairly consistent through the month, making it easier to plan what to wear. Nights drop to around 13°C (55°F), which is noticeably cooler than the daytime. A light jacket for the evening is a sensible addition, and the cool nights tend to make sleeping comfortable. On average, it has the peak temperatures of the year.

Sunshine in San Mateo in September

Enjoy a sunny month with about 270 hours of sunshine, the clear skies make San Mateo even more beautiful.

Wind Speed in San Mateo in September

September has wind speeds averaging 5 m/s (10 knots). You can expect gentle to moderate winds that move small trees and make flags wave steadily on typical days. Conditions typically range from light breezes to moderate winds.

Average water temperature in September

The water is 14°C (57°F) this month — cool enough to feel refreshing on a warm day, but cold enough that most people won't stay in for long without a wetsuit.

So this is a great month to visit if you prefer dry days with pleasant temperatures.

Select a Month

Check the conditions for any month of the year.

• January
• February
• March
• April

• May
• June
• July
• August

• September
• October
• November
• December

For a detailed overview over the year and the best time to visit the United States of America, check out our San Mateo's climate page.

San Mateo Temperature in September

Min Temperature 13°C (55°F)  

Max Temperature 24°C (75°F)  

Water Temperature 14°C (57°F) *  

Chance of Rain 3%  

Precipitation 3.5 mm (0.1 in)  

Rainy days a single day  

Humidity 73% *  

Windspeed 5 m/s (10 knots) *  

Sunshine 270 hours *  

Percentage Sunshine 73% *  

* Data from: San Francisco, the United States of America (10 KM, 6 Miles).

What to Wear in San Mateo in September

For San Mateo in September, you'll want flexible clothing. It's wise to pack cotton shirts, comfortable shorts, and a pair of jeans for cooler evenings. A light sweater or jacket is useful for air-conditioned spaces (like buses) or unexpected cool moments. Almost no rain is expected, so no need to bring rain gear. The water temperature sits at about 14°C (57°F), which is too chilly for most people to enjoy swimming. Leave the swimsuit at home unless you love cold water. You'll definitely want to pack sunglasses and sunscreen. There will be plenty of bright sunshine this month.

What To Do in San Mateo in September

We rated the following activities from 1 (least suitable) to 10 (best) to do.

Swimming

10/10

Cycling

10/10

Walking

10/10

Barbeque

9/10

Camping

10/10

Outdoor sports

10/10

Select a Month

Check the conditions for any month of the year.

• January
• February
• March
• April

• May
• June
• July
• August

• September
• October
• November
• December

For a detailed overview over the year and the best time to visit the United States of America, check out our San Mateo's climate page.

More climate data for San Mateo

Temperature Rainfall Sunshine Humidity Wind Speed Water Temp

See the full San Mateo climate overview or explore weather in the United States of America.