San Francisco in Fall
In fall (September, October and November), San Francisco sees average daytime highs around 24°C and overnight lows near 17°C, with 1091 mm of rain over about 79 wet days across the season. It is the coldest season of the year and the wettest season of the year.
Across fall, daytime highs hold fairly steady around 24°C. The sky is clear or mostly clear about 2% of the time across fall, and the air most often feels humid.
Fall is San Francisco's 3rd-best season to visit on our travel score. For the whole year in context, see San Francisco's year-round climate.
- Avg daytime high
- 24°C
- coldest season of the year
- Avg overnight low
- 17°C
- Rainfall
- 1091 mm
- 79 wet days
- Avg wind
- 5 km/h
- Travel score
- 4.1
- 3rd-best season
- Months
- Sep · Oct · Nov
Temperature in San Francisco in Fall
Across fall, daytime highs hold fairly steady around 24°C.
A typical fall day in San Francisco reaches about 24°C and drops to 17°C overnight. The warmest of the three months is September, the coolest November.
San Francisco weather by month
How the three fall months (September, October and November) 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 Fall
The sky is clear or mostly clear about 2% of the time across fall.
Chance of precipitation in Fall
San Francisco gets around 1091 mm of rain over 79 wet days across fall. The line is the day-by-day chance of measurable precipitation.
Humidity in Fall
Most of fall feels humid — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Fall
Winds average 5 km/h across fall.
Sunrise & sunset in Fall
Daylight runs from about 12 h 12 min in early September to 11 h 30 min by late November. The lit band spans sunrise to sunset each day.
Solar energy in Fall
Average shortwave solar energy reaching the ground each day across fall, about 3.9 kWh/m².
Hazard calendar for San Francisco
In fall, San Francisco overlaps its rainy season season. The full year is below, with each hazard's peak months called out.
San Francisco's rainy season runs May–November, when most of the year's rain falls.
Is fall a good time to visit San Francisco?
Our two travel scores rate fall for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
fall is a reasonable time to visit San Francisco for sightseeing.
What to pack for San Francisco in Fall
From fall's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In fall, San Francisco sees daytime highs around 24°C and nights near 17°C. Pack rain gear. Worth having: light clothes. About 79 days see rain.
Sea temperature near San Francisco in Fall
The nearest coast averages about 28°C across fall — 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 Fall
Clear-sky midday UV across fall 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 Fall
Average fine-particle pollution (PM2.5) through the year — so you can see where fall 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.