San Mateo, CA weather in December
December in San Mateo: cool, with frequent rain. Highs 58°F, lows 45°F, about 11 wet days. It is one of the coolest months in San Mateo.
- Normal high
- 58°F
- Normal low
- 45°F
- Wet days
- 11
- 4.1 in total
- Muggy days
- 0
- dew point 65°F+
How December changes from start to finish
| December 1 | December 31 | |
|---|---|---|
| Normal high | 60°F | 57°F |
| Normal low | 46°F | 44°F |
| Chance of a wet day | 33% | 35% |
| Sunrise / sunset | 7:05 am / 4:51 pm | 7:23 am / 5:00 pm |
| Daylight | 9.8 h | 9.6 h |
Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Pacific Time).
A typical December day
- 6 am48°Fdew point 43°F
- 9 am50°Fdew point 44°F
- Noon54°Fdew point 44°F
- 3 pm56°Fdew point 44°F
- 6 pm53°Fdew point 45°F
- 9 pm51°Fdew point 44°F
NOAA hourly normals (local standard time) from San Francisco Intl Airport (5 mi away); average wind 7 mph; clear or few clouds in 32% of daytime hours, mostly cloudy or overcast in 54%.
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°F1 of 31
- Beach dayshigh 80-95°F, under 0.05 in of rain, afternoon wind under 15 mph0 of 31
- Hot dayshigh 90°F or more0 of 31
- Muggy daysdaily mean dew point 65°F or more0 of 31
- Wet daysat least 0.01 in of rain or melted snow11 of 31
- Notable rainat least 0.10 in7 of 31
- Freezing nightslow 32°F or below0 of 31
Average days per December, counted from daily records for each year 1991-2020.
Rain in December
Normal precipitation is 4.1 in; a dry December brings about 1.8 in and a wet one about 6.4 in (25th and 75th percentiles). About 3 days bring half an inch or more, and about 1 an inch or more. Snow is very rare.
How December varies from year to year
- Warmest December, 1991-20202014: average high 62°F
- Coolest December1994: average high 53°F
- Wettest December2002: 10.8 in
- Driest December2017: 0.07 in
- Highest reading73°F (December 7, 2020)
- Lowest reading31°F (December 24, 1998)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
December compared with November and January
| November | December | January | |
|---|---|---|---|
| Normal high | 64°F | 58°F | 58°F |
| Normal low | 49°F | 45°F | 45°F |
| Wet days | 7 | 11 | 11 |
| Comfortable days | 11 | 1 | 2 |
| Daylight | 10.2 h | 9.6 h | 9.9 h |
Highs change by -6°F from November and 0°F into January.
Nearby alternatives in December
- Warmer: Santa Maria, CA209 mi · high 64°F · 7 wet days
- Drier: Fresno, CA151 mi · high 55°F · 7 wet days
- Cooler: Yosemite Valley, CA151 mi · high 46°F · 9 wet days
How San Mateo ranks in December
- Normal high128th warmest of 378 cities; 40th of 60 in California
- Wet days271st driest of 378
- Comfortable days191st most of 340
What to pack for San Mateo in December
- A rain jacket or umbrella – rain on about 11 days
Heating and cooling
December has 422 heating degree days and 0 cooling degree days (base 65°F), 16% of the year's total heating and cooling demand.
Questions
How cold is San Mateo in December?
The normal high is 58°F and the normal low is 45°F. From 1991 to 2020 the coldest December reading was 31°F (most recently on December 24, 1998).
Does it rain a lot in San Mateo in December?
About 11 days in December have at least 0.01 in of precipitation, and the normal total is 4.1 in. The wettest December in 1991-2020 was in 2002 (10.8 in); the driest was in 2017 (0.07 in).
Is December a good time to visit San Mateo?
December ranks 12th of 12 months on our comfort score for San Mateo (43 out of 100). It has about 1 comfortable day. The best months are July and August.
Where the numbers come from
- Temperature, rain, frost dates, humidity and wind by hour and cloud cover: San Francisco Intl Airport (USW00023234), 4.5 mi NNW of the city center, 8 ft . NOAA normals and daily records, 1991-2020.
- Snowfall and snow depth: Redwood City (USC00047339), 7.6 mi SE of the city center, 31 ft . NOAA normals and daily records, 1991-2020.
- Daily humidity and wind: San Francisco International Airport (724940-23234), 4.5 mi NNW of the city center, 10 ft . Hourly observations, 1991-2020.