San Francisco in Winter
In winter (December, January and February), San Francisco sees average daytime highs around 25°C and overnight lows near 16°C, with 121 mm of rain over about 21 wet days across the season. It is the 2nd-warmest season and the driest season of the year.
Across winter, daytime highs hold fairly steady around 25°C. The sky is clear or mostly clear about 41% of the time across winter, and the air most often feels comfortable.
Winter is San Francisco's best season of the year to visit on our travel score. For the whole year in context, see San Francisco's year-round climate.
- Avg daytime high
- 25°C
- 2nd-warmest season
- Avg overnight low
- 16°C
- Rainfall
- 121 mm
- 21 wet days
- Avg wind
- 9 km/h
- Travel score
- 7.6
- best season of the year
- Months
- Dec · Jan · Feb
Temperature in San Francisco in Winter
Across winter, daytime highs hold fairly steady around 25°C.
A typical winter day in San Francisco reaches about 25°C and drops to 16°C overnight. The warmest of the three months is February, the coolest January.
San Francisco weather by month
How the three winter months (December, January and February) compare with the rest of the year — the season's months are highlighted.
| Month | High / Low (°C) | Rainfall (mm) | Wet days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|
| Jan | 25° / 16° | 29 | 5.8 | 11.5 | 7.8 |
| Feb | 25° / 16° | 20 | 4.1 | 11.7 | 8.0 |
| Mar | 26° / 17° | 20 | 5.2 | 11.9 | 7.5 |
| Apr | 27° / 17° | 62 | 11.2 | 12.2 | 6.2 |
| May | 25° / 18° | 333 | 24.7 | 12.5 | 4.2 |
| Jun | 25° / 18° | 390 | 27.3 | 12.6 | 3.8 |
| Jul | 24° / 18° | 267 | 25 | 12.5 | 4.3 |
| Aug | 25° / 18° | 352 | 26.4 | 12.3 | 4.0 |
| Sep | 24° / 17° | 424 | 28.3 | 12.1 | 3.7 |
| Oct | 24° / 17° | 444 | 28.8 | 11.8 | 3.8 |
| Nov | 24° / 17° | 224 | 21.5 | 11.5 | 4.8 |
| Dec | 24° / 17° | 72 | 10.8 | 11.4 | 6.9 |
Cloud cover in Winter
The sky is clear or mostly clear about 41% of the time across winter.
Chance of precipitation in Winter
San Francisco gets around 121 mm of rain over 21 wet days across winter. The line is the day-by-day chance of measurable precipitation.
Humidity in Winter
Most of winter feels comfortable — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Winter
Winds average 9 km/h across winter.
Sunrise & sunset in Winter
Daylight runs from about 11 h 30 min in early December to 11 h 48 min by late February. The lit band spans sunrise to sunset each day.
Solar energy in Winter
Average shortwave solar energy reaching the ground each day across winter, about 4.9 kWh/m².
Hazard calendar for San Francisco
None of San Francisco's seasonal hazards peak in winter. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do.
San Francisco's rainy season runs May–November, when most of the year's rain falls.
Is winter a good time to visit San Francisco?
Our two travel scores rate winter for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
winter 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 Winter
From winter's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In winter, San Francisco sees daytime highs around 25°C and nights near 16°C. Worth packing: light clothes, rain gear and sun protection. About 21 days see rain.
Sea temperature near San Francisco in Winter
The nearest coast averages about 29°C across winter — 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.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 29 | 29 | 29 | 29 | 29 | 29 | 29 | 29 | 29 | 28 | 28 | 28 |
| Comfort | Tropical | Tropical | Tropical | Tropical | Tropical | Tropical | Tropical | Tropical | Tropical | Tropical | Warm | Tropical |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 29 | Tropical |
| Feb | 29 | Tropical |
| Mar | 29 | Tropical |
| Apr | 29 | Tropical |
| May | 29 | Tropical |
| Jun | 29 | Tropical |
| Jul | 29 | Tropical |
| Aug | 29 | Tropical |
| Sep | 29 | Tropical |
| Oct | 28 | Tropical |
| Nov | 28 | Warm |
| Dec | 28 | Tropical |
UV index in San Francisco in Winter
Clear-sky midday UV across winter averages 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.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 12 | 14 | 15 | 14 | 13 | 13 | 13 | 13 | 13 | 12 | 12 | 10 |
| Level | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 12 | Extreme |
| Feb | 14 | Extreme |
| Mar | 15 | Extreme |
| Apr | 14 | Extreme |
| May | 13 | Extreme |
| Jun | 13 | Extreme |
| Jul | 13 | Extreme |
| Aug | 13 | Extreme |
| Sep | 13 | Extreme |
| Oct | 12 | Extreme |
| Nov | 12 | Extreme |
| Dec | 10 | Extreme |
Air quality in San Francisco in Winter
Average fine-particle pollution (PM2.5) through the year — so you can see where winter 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).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 9 | 10 | 11 | 17 | 19 | 17 | 18 | 17 | 16 | 14 | 12 | 10 |
| Level | Good | Good | Good | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 9 | Good |
| Feb | 10 | Good |
| Mar | 11 | Good |
| Apr | 17 | Moderate |
| May | 19 | Moderate |
| Jun | 17 | Moderate |
| Jul | 18 | Moderate |
| Aug | 17 | Moderate |
| Sep | 16 | Moderate |
| Oct | 14 | Moderate |
| Nov | 12 | Good |
| Dec | 10 | Good |
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.
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
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.