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Weather in San Mateo County, California for December 2025

Your guide to San Mateo County weather in December - trends and predictions

    Temperatures

  • Until now, December 2025 in San Mateo County has been nearly identical to the historical average, with a temperature of 13.5 °F (showing only a slight deviation of 0 °F).

  • The forecast for the upcoming days in San Mateo County predicts a temperature of 15.4 °F, which is slightly above the historical average.

  • In general, the average temperature in San Mateo County at the beginning of December is 13.7 °F. As the month progressed, temperatures tended to moderately fall, reaching an average of 11.7 °F by the end of December.

    • Rain 🌧️

  • The climate of San Mateo County in December is notably wet, with an average of 11 rainy days, and a total of 172.9 mm of precipitation.

    • More

  • New! Chat with our AI weatherman - it’s amazing and free.

Average dry days
20
Dry days
Average rainy days
11
Rainy days
Average snowy days
0
Snow days
Average temperatures
13°/9°
Temperatures
Average wind speed
14 km/h
Avg max wind
Average humidity
86 %
Avg humidity

San Mateo County Weather December

Move between months or click on a day
November
January
Sun.Mon.Tue.Wed.Thu.Fri.Sat.
1
Heavy rain at times
16°
2
Cloudy
13°
3
Overcast
14°
4
Cloudy
15°
5
Overcast
13°
6
Overcast
13°
7
Overcast
12°
8
Overcast
12°
9
Partly cloudy
12°
10
Sunny
17°
11
Partly cloudy
15°
12
Mist
17°
13
Sunny
17°
14
Sunny
17°
15
Sunny
17°
16
Partly cloudy
17°
17
Patchy rain possible
15°
18
Sunny
16°
19
Patchy rain possible
17°
20
Patchy rain possible
13°
21
Patchy rain possible
13°
22
Patchy rain possible
12°
23
Patchy rain possible
12°
24
Moderate or heavy rain shower
14°
25
Overcast
10°
26
Moderate or heavy rain shower
13°
27
Moderate or heavy rain shower
14°
28
Moderate rain at times
14°
29
Moderate or heavy rain shower
13°
30
Overcast
11°
31
Fog
7°

Temperatures trend during December in San Mateo County

See the weather trend as well as the moving average line

December weather in San Mateo County day by day

Click on a date for more information
November January
Date Weather Temperatures Rain UV More
Dec. 1 Heavy rain at times
Heavy rain at times
 16° /8° 0.6 mm 4
Dec. 2 Cloudy
Cloudy
 13° /6° 0 mm 3
Dec. 3 Overcast
Overcast
 14° /7° 0 mm 4
Dec. 4 Cloudy
Cloudy
 15° /7° 0 mm 4
Dec. 5 Overcast
Overcast
 13° /8° 0 mm 3
Dec. 6 Overcast
Overcast
 13° /9° 0 mm 3
Dec. 7 Overcast
Overcast
 12° /8° 0 mm 3
Dec. 8 Overcast
Overcast
 12° /8° 0 mm 3
Dec. 9 Partly cloudy
Partly cloudy
 12° /8° 0 mm 4
Dec. 10 Sunny
Sunny
 17° /7° 0 mm 0.4
Dec. 11 Partly cloudy
Partly cloudy
 15° /5° 0 mm 0.5
Dec. 12 Mist
Mist
 17° /6° 0 mm 0.4
Dec. 13 Sunny
Sunny
 17° /8° 0 mm 0.4
Dec. 14 Sunny
Sunny
 17° /10° 0 mm 0.5
Dec. 15 Sunny
Sunny
 17° /11° 0 mm 0
Dec. 16 Partly cloudy
Partly cloudy
 17° /12° 0 mm 4
Dec. 17 Patchy rain possible
Patchy rain possible
 15° /12° 0.4 mm 3
Dec. 18 Sunny
Sunny
 16° /11° 0 mm 4
Dec. 19 Patchy rain possible
Patchy rain possible
 17° /11° 2.7 mm 3
Dec. 20 Patchy rain possible
Patchy rain possible
 13° /9° 2.4 mm 3
Dec. 21 Patchy rain possible
Patchy rain possible
 13° /8° 0.7 mm 3
Dec. 22 Patchy rain possible
Patchy rain possible
 12° /9° 1.9 mm 2
Dec. 23 Patchy rain possible
Patchy rain possible
 12° /7° 1.3 mm 2
Dec. 24 Moderate or heavy rain shower
Moderate or heavy rain shower
 14° /10° 31 mm 3
Dec. 25 Overcast
Overcast
 10° /7° 0 mm 3
Dec. 26 Moderate or heavy rain shower
Moderate or heavy rain shower
 13° /9° 11.8 mm 3
Dec. 27 Moderate or heavy rain shower
Moderate or heavy rain shower
 14° /12° 29.2 mm 3
Dec. 28 Moderate rain at times
Moderate rain at times
 14° /11° 1.3 mm 3
Dec. 29 Moderate or heavy rain shower
Moderate or heavy rain shower
 13° /9° 6.5 mm 3
Dec. 30 Overcast
Overcast
 11° /7° 0 mm 3
Dec. 31 Fog
Fog
 7° /3° 0 mm 2
Next
Important Notice
Our weather forecast for San Mateo County in December is based on the analysis of historical data rather than real-time forecast models. While this provides a general overview, weather conditions can change. We recommend that you check the San Mateo County forecast closer to your planned date for the most up-to-date weather information.
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San Mateo County in December - FAQ

What are the expected maximum and minimum temperatures in San Mateo County during December?
During December, expect a variety of temperatures with highs around 13° and lows near 9°, suitable for diverse activities and preferences.
How much rainfall should be expected in San Mateo County during December?
Significant rainfall exceeding 172.9 mm is expected in San Mateo County during December, occurring over more than 11 days. Preparing for wet conditions is recommended in your planning.
What are the typical wind conditions in San Mateo County during December?
The average wind speed in San Mateo County during December is 14 km/h, suggesting breezy to windy conditions, depending on your activities.

December rainfall patterns in San Mateo County

Explore the daily rainfall trends and prepare for San Mateo Countys December weather 💧
Typically, San Mateo County has 11 rainy days in December with a total of 172.9 mm of rainfall.
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Location coordinates Where is San Mateo County?

Get accurate weather forecasts for San Mateo County, located at latitude 37.563 and longitude -122.326. Stay updated with localized weather information tailored for San Mateo County.

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