Santa Rosa Weather in December

NASA POWER reanalysis for the half-degree grid cell around Santa Rosa, 1991-2020; a grid cell is an area average and can differ from a thermometer in town by several degrees

Average highs run from 24°C on December 1 to 23°C on December 31, and lows from 16°C to 16°C. Normal precipitation for the month is 59 mm over about 12 wet days.

December day by day

The normal high and low for each date, in °C.

Normal low
Normal high
Reanalysis extreme high
Reanalysis extreme low

December at a glance

Average high: 24°C
Average low: 16°C
Precipitation: 59 mm
Reanalysis high: 29°CDec 9, 2018
Reanalysis low: 13°CDec 24, 1998
Daylight: 12 h 43 min to 12 h 45 min
Cloud cover: 87%
Humidity: 79%
Dew point: 15°C
Wind: 6.5 km/h

Every day of the month

A wet day has at least 1 mm of precipitation in the reanalysis.

Date	Normal high	Normal low	Reanalysis high	Reanalysis low	Chance wet
Dec 1	24°C	16°C	26°C 1991	15°C 1996	35%
Dec 2	24°C	16°C	27°C 2013	14°C 1992	36%
Dec 3	24°C	16°C	28°C 2011	14°C 1992	38%
Dec 4	24°C	16°C	27°C 2015	14°C 1995	38%
Dec 5	24°C	16°C	28°C 2011	14°C 2014	38%
Dec 6	24°C	16°C	26°C 1997	14°C 2004	40%
Dec 7	24°C	16°C	27°C 2017	14°C 1996	40%
Dec 8	24°C	16°C	28°C 1994	14°C 2008	40%
Dec 9	24°C	16°C	29°C 2018	14°C 2018	39%
Dec 10	24°C	16°C	28°C 2018	15°C 2016	39%
Dec 11	24°C	16°C	28°C 1997	14°C 1996	39%
Dec 12	24°C	16°C	29°C 1997	15°C 1996	40%
Dec 13	24°C	16°C	28°C 2002	15°C 2003	41%
Dec 14	24°C	16°C	28°C 2015	14°C 2001	42%
Dec 15	24°C	16°C	27°C 2020	15°C 1998	42%
Dec 16	24°C	16°C	27°C 2016	15°C 2007	42%
Dec 17	24°C	16°C	28°C 1997	14°C 2001	43%
Dec 18	24°C	16°C	28°C 1991	14°C 1991	43%
Dec 19	24°C	16°C	27°C 2002	14°C 2003	44%
Dec 20	24°C	16°C	28°C 1992	15°C 2015	45%
Dec 21	24°C	16°C	27°C 1992	14°C 2007	46%
Dec 22	24°C	16°C	27°C 2005	14°C 2017	45%
Dec 23	24°C	16°C	28°C 1997	14°C 1998	45%
Dec 24	23°C	16°C	27°C 1997	13°C 1998	45%
Dec 25	23°C	16°C	27°C 2000	13°C 2013	45%
Dec 26	23°C	16°C	27°C 2001	14°C 2013	45%
Dec 27	23°C	16°C	27°C 1997	14°C 1999	45%
Dec 28	23°C	16°C	27°C 1997	14°C 2008	44%
Dec 29	23°C	16°C	27°C 1997	14°C 1995	43%
Dec 30	23°C	16°C	27°C 1997	14°C 2000	43%
Dec 31	23°C	16°C	27°C 1997	14°C 2000	42%

Chance of rain

Chance of a wet day

Sunrise and sunset

Times for 2026, local time (GMT-5).

December 1: sunrise 5:27 AM, sunset 6:10 PM
December 31: sunrise 5:40 AM, sunset 6:25 PM

Every day of December: sun and moon

Other months

Sources

Cloud, humidity, wind and sunshine, and temperature and precipitation: NASA POWER (MERRA-2, CERES and GEWEX SRB), 1991-2020. The data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division: POWER Daily API v2, accessed 2026-09-24. Sun and moon: computed with the NOAA solar equations and Meeus.