San Mateo Weather in December

December in San Mateo typically sees daytime highs of 15°C (59°F) and nighttime lows of 6°C (43°F). As the wettest month of the year, expect more rainfall than other months.

Rainfall in San Mateo in December

During the wettest month of the year, an umbrella can be your best friend to stay dry. Typically around 13 days of rainfall are expected, averaging 99 mm (3.9 in) for the month. The rain this month tends to fall in heavier spells rather than light drizzle. When it rains, showers can be significant.

Temperature in San Mateo in December

In December, San Mateo sees moderate temperatures, with highs of 15°C (59°F). Nights drop to around 6°C (43°F). Even when the weather is stable, mornings and evenings can still feel distinctly cool. Nights drop to 6°C (43°F). Cold nights like these are actually great for sleeping well, as long as you have a warm enough duvet. December has the coolest temperatures of the year, but still offering mild weather.

Sunshine in San Mateo in December

The month experiences a moderate amount of sunlight, with 160 hours of sunshine. This provides a nice balance between sunshine and clouds.

Wind Speed in San Mateo in December

Average wind speeds reach 3 m/s (6 knots) in December, creating light breezes that feel pleasant throughout the day. Some days are calmer, while others bring slightly more active breezes.

Average water temperature in December

At 13°C (55°F), the water is cool but manageable for those who don't mind a bit of a shock getting in. Most people adjust after a few minutes.

Our weather planner can help you find worldwide destinations with pleasant weather during this period. May, June, July, August, September and October typically offer the best weather for San Mateo.

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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 December

Min Temperature 6°C (43°F)  

Max Temperature 15°C (59°F)  

Water Temperature 13°C (55°F) *  

Chance of Rain 43%  

Precipitation 99 mm (3.9 in)  

Rainy days 13 days  

Humidity 78% *  

Windspeed 3 m/s (6 knots) *  

Sunshine 160 hours *  

Percentage Sunshine 54% *  

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

What to Wear in San Mateo in December

The weather can be unpredictable in December, so pack clothes you can easily mix and match. You could bring jeans, other long pants, and a few t-shirts. A light jacket or light sweater will be pleasant for the cooler moments. High rain levels are expected, so pack waterproof gear and an umbrella or poncho. Expect water temperatures of around 13°C (55°F), which is definitely too cold for comfortable swimming. Your luggage space is better used for other items. Bring sunglasses since you'll have some sunny periods throughout the month

What To Do in San Mateo in December

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

Swimming

5/10

Cycling

6/10

Walking

6/10

Camping

4/10

Outdoor sports

9/10

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.