San Juan Weather in December

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

Average highs run from 29°C on December 1 to 29°C on December 31, and lows from 23°C to 23°C. Normal precipitation for the month is 257 mm over about 22 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: 29°C
Average low: 23°C
Precipitation: 257 mm
Reanalysis high: 34°CDec 4, 2011
Reanalysis low: 21°CDec 18, 2000
Daylight: 12 h 20 min to 12 h 20 min
Cloud cover: 82%
Humidity: 90%
Dew point: 24°C
Wind: 2.5 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	29°C	23°C	32°C 1993	22°C 1993	65%
Dec 2	29°C	23°C	32°C 1993	22°C 1999	66%
Dec 3	29°C	23°C	34°C 2011	22°C 2003	67%
Dec 4	29°C	23°C	34°C 2011	22°C 2016	67%
Dec 5	29°C	23°C	33°C 2011	22°C 2013	67%
Dec 6	29°C	23°C	32°C 1993	22°C 2014	67%
Dec 7	29°C	23°C	32°C 2012	22°C 1994	66%
Dec 8	29°C	23°C	32°C 2011	21°C 1994	67%
Dec 9	29°C	23°C	32°C 1992	22°C 2020	66%
Dec 10	29°C	23°C	32°C 1992	22°C 2008	67%
Dec 11	29°C	23°C	32°C 1992	22°C 1996	67%
Dec 12	29°C	23°C	31°C 1991	22°C 1996	68%
Dec 13	29°C	23°C	32°C 1991	22°C 1993	68%
Dec 14	29°C	23°C	31°C 1992	21°C 1994	68%
Dec 15	29°C	23°C	31°C 1992	21°C 2000	68%
Dec 16	29°C	23°C	32°C 1992	21°C 2000	69%
Dec 17	29°C	23°C	32°C 1994	22°C 2000	69%
Dec 18	29°C	23°C	31°C 2010	21°C 2000	68%
Dec 19	29°C	23°C	32°C 1992	22°C 2003	69%
Dec 20	29°C	23°C	33°C 1993	22°C 1995	69%
Dec 21	29°C	23°C	32°C 1992	21°C 1995	69%
Dec 22	29°C	23°C	32°C 1993	22°C 2006	70%
Dec 23	29°C	23°C	32°C 1991	22°C 2005	70%
Dec 24	29°C	23°C	32°C 1991	22°C 1998	70%
Dec 25	29°C	23°C	32°C 2012	21°C 1998	69%
Dec 26	29°C	23°C	31°C 1993	22°C 1995	69%
Dec 27	29°C	23°C	32°C 1993	22°C 1999	69%
Dec 28	29°C	23°C	32°C 1993	21°C 2005	69%
Dec 29	29°C	23°C	32°C 1993	22°C 1999	70%
Dec 30	29°C	23°C	32°C 1992	22°C 2005	70%
Dec 31	29°C	23°C	31°C 2010	22°C 2000	70%

Chance of rain

Chance of a wet day

Sunrise and sunset

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

December 1: sunrise 5:32 AM, sunset 5:52 PM
December 31: sunrise 5:46 AM, sunset 6:06 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.