Vallejo, CA weather in December
Vallejo is cool in December, with frequent rain: highs average 59°F and nights drop to about 40°F. Rain falls on about 10 days. It is one of the coolest months in Vallejo.
- Normal high
- 59°F
- Normal low
- 40°F
- Wet days
- 10
- 3.8 in total
- Muggy days
- 0
- dew point 65°F+
How December changes from start to finish
| December 1 | December 31 | |
|---|---|---|
| Normal high | 61°F | 58°F |
| Normal low | 41°F | 39°F |
| Chance of a wet day | 31% | 34% |
| Sunrise / sunset | 7:06 am / 4:49 pm | 7:25 am / 4:58 pm |
| Daylight | 9.7 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 am41°Fdew point 38°F
- 9 am45°Fdew point 41°F
- Noon54°Fdew point 42°F
- 3 pm56°Fdew point 41°F
- 6 pm48°Fdew point 41°F
- 9 pm45°Fdew point 40°F
NOAA hourly normals (local standard time) from Travis AFB (21 mi away); average wind 7 mph; clear or few clouds in 48% of daytime hours, mostly cloudy or overcast in 45%.
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°F3 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 snow10 of 31
- Notable rainat least 0.10 in7 of 31
- Freezing nightslow 32°F or below5 of 31
Average days per December, counted from daily records for each year 1991-2020.
Rain in December
Normal precipitation is 3.8 in; a dry December brings about 1.7 in and a wet one about 6.1 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, 1991-20201999: average high 63°F
- Coolest December1994: average high 54°F
- Wettest December2005: 10.8 in
- Driest December2011: 0.06 in
- Highest reading76°F (December 20, 1999)
- Lowest reading22°F (December 22, 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 | 66°F | 59°F | 59°F |
| Normal low | 44°F | 40°F | 40°F |
| Wet days | 7 | 10 | 11 |
| Comfortable days | 16 | 3 | 5 |
| Daylight | 10.1 h | 9.6 h | 9.9 h |
Highs change by -7°F from November and 0°F into January.
Nearby alternatives in December
- Warmer: Santa Maria, CA240 mi · high 64°F · 7 wet days
- Drier: Reno, NV164 mi · high 47°F · 7 wet days
- Cooler: South Lake Tahoe, CA136 mi · high 43°F · 11 wet days
How Vallejo ranks in December
- Normal high125th warmest of 378 cities; 37th of 60 in California
- Wet days236th driest of 378
- Comfortable days163rd most of 340
What to pack for Vallejo in December
- A warm jacket – lows near 40°F, highs near 59°F
- A rain jacket or umbrella – rain on about 10 days
Heating and cooling
December has 493 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 Vallejo in December?
The normal high is 59°F and the normal low is 40°F. From 1991 to 2020 the coldest December reading was 22°F (December 22, 1998).
Does it rain a lot in Vallejo in December?
About 10 days in December have at least 0.01 in of precipitation, and the normal total is 3.8 in. The wettest December in 1991-2020 was in 2005 (10.9 in); the driest was in 2011 (0.06 in).
Does it snow in Vallejo in December?
Snow is very rare: the 1991-2020 normal for December rounds to 0.0 in.
Is December a good time to visit Vallejo?
December ranks 12th of 12 months on our comfort score for Vallejo (44 out of 100). It has about 3 comfortable days. The best month is May.
Where the numbers come from
- Temperature: Napa State Hospital (USC00046074), 12 mi N of the city center, 35 ft . NOAA normals and daily records, 1991-2020.
- Rain: Martinez WTP (USC00045378), 10 mi SE of the city center, 40 ft . NOAA normals and daily records, 1991-2020.
- Snowfall and snow depth: Fairfield (USC00042934), 16 mi NE of the city center, 40 ft . NOAA normals and daily records, 1991-2020.
- Frost dates: Napa Co Airport (USW00093227), 7.5 mi NNW of the city center, 14 ft (55 ft lower than the city). NOAA normals and daily records, 1991-2020.
- Humidity and wind by hour and cloud cover: Travis AFB (USW00023202), 21 mi ENE of the city center, 59 ft . NOAA normals and daily records, 1991-2020.
- Daily humidity and wind: Napa County Airport (724955-93227), 7.3 mi N of the city center, 15 ft (54 ft lower than the city). Hourly observations, 1991-2020.