San Mateo, CA weather in January
San Mateo is cool in January, with frequent rain: highs average 58°F and nights drop to about 45°F. There are about 11 days with rain. It is one of the coolest months in San Mateo.
- Normal high
- 58°F
- Normal low
- 45°F
- Wet days
- 11
- 3.9 in total
- Muggy days
- 0
- dew point 65°F+
How January changes from start to finish
| January 1 | January 31 | |
|---|---|---|
| Normal high | 57°F | 59°F |
| Normal low | 44°F | 45°F |
| Chance of a wet day | 35% | 35% |
| Sunrise / sunset | 7:24 am / 5:01 pm | 7:13 am / 5:31 pm |
| Daylight | 9.6 h | 10.3 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 January day
- 6 am47°Fdew point 43°F
- 9 am50°Fdew point 44°F
- Noon53°Fdew point 45°F
- 3 pm55°Fdew point 45°F
- 6 pm53°Fdew point 45°F
- 9 pm51°Fdew point 45°F
NOAA hourly normals (local standard time) from San Francisco Intl Airport (5 mi away); average wind 7 mph; clear or few clouds in 29% of daytime hours, mostly cloudy or overcast in 57%.
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°F2 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 January, counted from daily records for each year 1991-2020.
Rain in January
Normal precipitation is 3.9 in; a dry January brings about 1.2 in and a wet one about 5.9 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 January varies from year to year
- Warmest January, 1991-20202014: average high 64°F
- Coolest January2008: average high 54°F
- Wettest January1993: 11.3 in
- Driest January2015: no measurable precipitation
- Highest reading74°F (January 31, 2015)
- Lowest reading32°F (January 14, 2007)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
January compared with December and February
| December | January | February | |
|---|---|---|---|
| Normal high | 58°F | 58°F | 61°F |
| Normal low | 45°F | 45°F | 46°F |
| Wet days | 11 | 11 | 11 |
| Comfortable days | 1 | 2 | 5 |
| Daylight | 9.6 h | 9.9 h | 10.8 h |
Highs change by 0°F from December and +3°F into February.
Nearby alternatives in January
- Warmer: Santa Maria, CA209 mi · high 65°F · 8 wet days
- Drier: Fresno, CA151 mi · high 55°F · 8 wet days
- Cooler: Yosemite Valley, CA151 mi · high 48°F · 9 wet days
How San Mateo ranks in January
- Normal high126th warmest of 378 cities; 43rd of 60 in California
- Wet days273rd driest of 378
- Comfortable days181st most of 339
What to pack for San Mateo in January
- A rain jacket or umbrella – rain on about 11 days
Heating and cooling
January has 426 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 January?
The normal high is 58°F and the normal low is 45°F. From 1991 to 2020 the coldest January reading was 32°F (January 14, 2007).
Does it rain a lot in San Mateo in January?
About 11 days in January have at least 0.01 in of precipitation, and the normal total is 3.9 in. The wettest January in 1991-2020 was in 1993 (11.3 in); the driest was in 2015, with no measurable precipitation.
Is January a good time to visit San Mateo?
January ranks 11th of 12 months on our comfort score for San Mateo (44 out of 100). It has about 2 comfortable days. 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.