Climate averages 1991–2020

San Diego weather
in January.

A mild, moderately wet month: the 10th warmest and the 11th driest of the year.

Long-term climate patterns, not a forecast for a particular trip.

Average high 17.4°C Daytime mean, January

Average low 8.7°C Night-time mean, January

Rainfall 50 mm 6 days with ≥1 mm

Daylight 10 h Sunrise to sunset, per day

January is a mild month in San Diego: daytime highs average 17.4°C and nights cool to about 8.7°C. By daytime temperature it is the 10th warmest of the 12 months.

Expect about 50 mm of rain on roughly 6 days, which makes January a moderately wet month (the 11th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 10 h 15 min on an average January day.

The nearest other city in this atlas is Chula Vista (11 km away). In January its highs average 17.1°C, about as warm as San Diego, with 57 mm of rain.

Among the 498 cities listed in the United States, San Diego ranks joint 87th of 498 for the warmest January highs and joint 117th of 498 for the driest January (rainfall, lowest first). The mean January high of those 498 cities is 9.5°C; San Diego is 7.9°C warmer than that mean.

From January to February, average highs fall by 0.2°C to 17.2°C, and monthly rainfall rises from 50 mm to 63 mm.

The annual picture

January in context

30-year average

Average highAverage low°C

Monthly rainfall

Average total · mm

Averages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated

Every month, side by side

San Diego climate table

1991–2020

Monthly climate averages for San Diego, 1991–2020
Month	Average highHigh / low	Average low	Rainfall mm/month	Rain days ≥1 mm/day	Daylight hours/dayDaylight h/day
January, selected	17.4°C8.7°C	8.7°C	50	5.5	10.310 h
February	17.2°C9.2°C	9.2°C	63	6.1	11.011 h
March	17.8°C10.4°C	10.4°C	38	5.2	12.012 h
April	19.1°C11.9°C	11.9°C	16	2.9	13.013 h
May	20.2°C13.6°C	13.6°C	7.1	1.6	13.814 h
June	22.0°C14.9°C	14.9°C	1.2	0.2	14.314 h
July	24.3°C17.1°C	17.1°C	1.3	0.3	14.114 h
August	25.4°C18.0°C	18.0°C	0.4	0.1	13.413 h
September	25.1°C17.5°C	17.5°C	2.9	0.6	12.412 h
October	23.0°C15.2°C	15.2°C	12	2.0	11.411 h
November	20.3°C11.7°C	11.7°C	19	2.9	10.511 h
December	17.3°C8.8°C	8.8°C	40	4.9	10.010 h

Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.

Compare places

January in nearby cities

Distance from San Diego

Read the numbers correctly

Climate, not a promise.

These patterns help compare months. They cannot tell you the weather on a specific day of your trip.

Sources, method and limits

How these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for San Diego) is explained once on the San Diego year overview and on the Sources, method and limits page.