San Francisco weather in January

In January, San Francisco sees average daytime highs of 25°C and overnight lows near 16°C, with 29 mm of rain across 5.8 wet days and about 11.5 hours of daylight. It is the 6th-warmest and 10th-wettest month of the year here.

Day-to-day highs hold fairly steady near 25°C through the month. The sky is clear or mostly clear about 45% of the time in January, and the air most often feels comfortable.

Daylight stretches from about 11 h 24 min at the start of January to 11 h 36 min by month's end. Set against the rest of the year, January is San Francisco's 2nd-clearest and 1st-windiest month. For the whole year in context, see San Francisco's year-round climate.

Daytime high
25°
6th warmest
Overnight low
16°
1st coldest
Rainfall
29 mm
5.8 wet days
Daylight
11 h 30 min
6:02 AM – 5:30 PM
Cloud cover
46%
2nd clearest
Wind
9 km/h
1st windiest
Solar energy
4.89 kWh/m²
Travel score
7.8
out of 10

Temperature in January

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 25°C through the month.

A typical January day in San Francisco reaches about 25°C in the afternoon and slips back to 16°C overnight — a 8°C spread between the day's warmth and the night's chill. On most days the high lands between 23°C and 26°C. Set against its neighbours, January runs on par with December and on par with February.

10°15°20°25°30°151015202531
Avg high (°C)Avg low (°C)
12417
22417
32417
42417
52417
62416
72416
82416
92416
102416
112416
122416
132416
142416
152416
162416
172416
182416
192516
202516
212516
222516
232516
242516
252516
262516
272516
282516
292516
302516
312516

San Francisco weather by month

How January compares with the rest of the year at a glance. January is the 6th-warmest and 10th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan25° / 16°295.811.57.8
Feb25° / 16°204.111.78.0
Mar26° / 17°205.211.97.5
Apr27° / 17°6211.212.26.2
May25° / 18°33324.712.54.2
Jun25° / 18°39027.312.63.8
Jul24° / 18°2672512.54.3
Aug25° / 18°35226.412.34.0
Sep24° / 17°42428.312.13.7
Oct24° / 17°44428.811.83.8
Nov24° / 17°22421.511.54.8
Dec24° / 17°7210.811.46.9

Cloud cover in January

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 45% of the time in January.

Beyond those clear spells, partly cloudy skies cover about 27% of January, with mostly cloudy or overcast conditions the remaining 28%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
17030
27030
37030
47030
57030
67129
77030
87030
96931
106931
116931
126931
136931
146832
156832
166931
177030
187129
197129
207327
217327
227426
237525
247624
257723
267822
277822
287921
298020
308020
318020

Chance of precipitation in January

Any precipitation

San Francisco gets around 29 mm of rain over 5.8 wet days in January. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 19% and peaks near 24% on the wettest days. The odds ease toward the end of the month.

0%10%20%30%151015202531
Rain chance (%)
124
223
323
423
522
622
722
822
922
1022
1122
1222
1322
1422
1521
1621
1720
1820
1919
2018
2118
2217
2316
2415
2514
2613
2713
2812
2912
3012
3112

Humidity in January

DryComfortableHumidMuggyOppressiveMiserable

Most of January feels comfortable — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, January lands in the comfortable band about 65% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)
1357400
2359380
3361360
4461350
5462340
6563320
7564310
8664300
9665290
10765280
11865270
12866260
13966250
141066240
151066240
161166230
171266220
181266220
191267210
201366210
211367200
221367200
231368190
241466191
251467181
261467181
271567171
281567171
291666171
301667161
311667161

Wind in January

Winds average 9 km/h in January, the windiest month of the year.

Across January, daily wind ranges from about 9 km/h on the calmest days to 9 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (km/h)Feels
19calm
29calm
39calm
49calm
59calm
69calm
79calm
89calm
99calm
109calm
119calm
129calm
139calm
149calm
159calm
169calm
179calm
189calm
199calm
209calm
219calm
229calm
239calm
249calm
259calm
269calm
279calm
289calm
299calm
309calm
319calm

Sunrise & sunset in January

DaylightNight

Daylight runs from about 11 h 24 min at the start of January to 11 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 12 minutes over January. Sunrise moves from 5:57 AM to 6:03 AM, and sunset from 5:22 PM to 5:37 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
111.45:575:22
211.45:575:23
311.45:585:23
411.45:585:24
511.45:585:24
611.45:595:25
711.45:595:26
811.45:595:26
911.46:005:27
1011.56:005:27
1111.56:005:28
1211.56:015:28
1311.56:015:29
1411.56:015:29
1511.56:015:30
1611.56:025:30
1711.56:025:31
1811.56:025:31
1911.56:025:31
2011.56:025:32
2111.56:025:32
2211.56:035:33
2311.56:035:33
2411.56:035:34
2511.56:035:34
2611.56:035:35
2711.56:035:35
2811.56:035:35
2911.56:035:36
3011.66:035:36
3111.66:035:37

Solar energy in January

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in January, about 4.89 kWh/m².

For context, solar energy here swings from a low near 3.65 kWh/m² to a high of 5.95 kWh/m² in March across the year — January's 4.89 kWh/m² falls in the middle.

0246151015202531
Solar energy (kWh/m²)Level
14.6Bright
24.6Bright
34.6Bright
44.6Bright
54.6Bright
64.7Bright
74.7Bright
84.7Bright
94.7Bright
104.7Bright
114.8Bright
124.8Bright
134.8Bright
144.8Bright
154.9Bright
164.9Bright
174.9Bright
184.9Bright
195.0Bright
205.0Bright
215.0Bright
225.0Bright
235.1Bright
245.1Bright
255.1Bright
265.2Bright
275.2Bright
285.2Bright
295.2Bright
305.3Bright
315.3Bright
Planning a trip in January

Hazard calendar for San Francisco

In seasonPeak

None of San Francisco's seasonal hazards are active in January. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do peak.

San Francisco's rainy season runs May–November, when most of the year's rain falls.

Rainy season
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is January a good time to visit San Francisco?

Our two travel scores rate January for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

7.8
Sightseeing
2nd-best month of the year
6.9
Beach & pool
3rd-best month of the year

January is one of the better times to visit San Francisco for general sightseeing. The water and warmth also suit a beach or pool day.

What to pack for San Francisco in January

From January's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In January, San Francisco sees daytime highs around 25°C and nights near 16°C. Worth packing: light clothes and sun protection. About 6 days see rain.

light clothessun protection

Sea temperature near San Francisco in January

The nearest coast averages about 29°C in January — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 56 km away) is warmest in April at about 29°C and coldest in November near 28°C.

The water stays above 20°C all year — warm enough for a swim any month.

26°28°30°JanFebMarAprMayJunJulAugSepOctNovDecwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan29Tropical
Feb29Tropical
Mar29Tropical
Apr29Tropical
May29Tropical
Jun29Tropical
Jul29Tropical
Aug29Tropical
Sep29Tropical
Oct28Tropical
Nov28Warm
Dec28Tropical

UV index in San Francisco in January

LowModerateHighVery highExtreme

Clear-sky midday UV in January peaks around 12 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in San Francisco peaks around March 19 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 16 at about 10 (extreme).

The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeMar 19UV 15Dec 16UV 10
UV index (midday)Level
Jan12Extreme
Feb14Extreme
Mar15Extreme
Apr14Extreme
May13Extreme
Jun13Extreme
Jul13Extreme
Aug13Extreme
Sep13Extreme
Oct12Extreme
Nov12Extreme
Dec10Extreme

Air quality in San Francisco in January

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where January falls, not just the annual average.

Air quality in San Francisco is worst in May — around 19 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (January, 9 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodMay 1718 µg/m³Jan 149 µg/m³
PM2.5 (µg/m³)Level
Jan9Good
Feb10Good
Mar11Good
Apr17Moderate
May19Moderate
Jun17Moderate
Jul18Moderate
Aug17Moderate
Sep16Moderate
Oct14Moderate
Nov12Good
Dec10Good
Location & terrain

Where is San Francisco?

San Francisco sits at 10.0°N, 84.1°W, 1,131 m above sea level, in Costa Rica. The nearest listed city is Heredia, 1.0 km away.

Topography around San Francisco

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of San Francisco.

Within 3 km, the terrain around San Francisco has significant variations in elevation — a maximum elevation change of 271 m around an average of 1,102 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 2,296 m; within 80 km, extreme variations in elevation — a maximum elevation change of 3,470 m.

The land around San Francisco is covered by artificial surfaces (68%) and trees (22%) within 3 km, trees (56%) and artificial surfaces (29%) within 16 km, and trees (70%) within 80 km.

3 km
271 m
16 km
2,296 m
80 km
3,470 m
treesgrasslandcroplandartificial surfaceswater
January weather nearby: Heredia 1.0 km · Mercedes Norte 1.0 km · San Pablo 3.0 km · San Juan 6.0 km · Colima 7.0 km · San Rafael 7.0 km · San Jose 8.0 km · Calle Blancos 9.0 km

Costa Rica travel facts

Travel advisory
Level 2
Exercise Increased Caution
Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 59% of US
price level, 2025
GDP per capita
$19,970
2025
Happiness
7.4 / 10
World Happiness, 2025
Safe drinking water
81%
of population, 2024
Homicide rate
17.7
per 100k, 2023
Road deaths
14.8
per 100k/yr, 2019
Income group
High
World Bank
English
Moderate
EF EPI 516
Religion
Roman Catholic 48%none 27%Evangelical and Pentecostal 20%other 3%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for San Francisco (9.9938°, -84.1274°, elevation 1,131 m), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).