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San Francisco in September: weather, sea & travel advice
This month's data profile
Strong month under the current formula
San Francisco in September is climatically well suited to city breaks, active holidays and hiking, family holidays and beach holidays. The average daily high is around 24 °C, and the sea is about 15 °C. With about 1 rainy day it is very dry.
Historical monthly averages, not a weather forecast. Individual days and years can differ substantially.
Rank among 12 monthly averages
80/100 · #1
Warmth
#1
Dryness
#3
Sun
#6
Sea warmth
#1
Published best categories: Overall, Beach, City break, Family
San Francisco · SeptemberPhoto: Dale Cruse · CC BY 2.0Climate facts
- Average high
- 24 °C
- Average low
- 13 °C
- Sea
- 15 °C
- Rainy days (est.)
- 1 rainy day (est.)
- Sun (est.)
- 7 h/day
- Humidity
- 70 %
Climate evidence with direct month comparison
The highlighted row is the selected month. Precipitation total and rainy days are separate monthly averages.
| Month | Avg high °C | Avg low °C | Rainy days (est.) | Precipitation mm | Sun h/day (est.) | Humidity % | Wind m/s | Sea °C | Score |
|---|---|---|---|---|---|---|---|---|---|
| August | 24 | 13 | 0 | 2 | 8.8 | 73 | 2.3 | 14 | 79 |
| September (selected) | 24 | 13 | 1 | 4 | 7.2 | 70 | 2.0 | 15 | 80 |
| October | 22 | 12 | 4 | 33 | 5.2 | 70 | 1.9 | 14 | 76 |
How do the previous and next months compare?
Baseline: September (80/100)
Positive and negative values show the change from the selected month.
| Score Δ | Average high Δ | Average low Δ | Rainy days Δ | Rain Δ | Sun Δ | Humidity Δ | Wind Δ | Sea Δ | |
|---|---|---|---|---|---|---|---|---|---|
| August | -1 | -0.6 °C | -0.2 °C | -0.7 | -2.8 mm | +1.6 h | +2.7 % | +0.2 m/s | -0.2 °C |
| October | -4 | -2 °C | -1.3 °C | +2.6 | +28.2 mm | -2 h | -0.5 % | -0.1 m/s | -0.6 °C |
All twelve months in context
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Frequently asked questions
How warm is San Francisco in September?
The average daily high is around 24 °C, with an average daily low of about 13 °C.
Can you swim in San Francisco in September?
The sea is about 15 °C (cold).
Does it rain a lot in San Francisco in September?
The curated estimate is about 1 rainy day per month, not a directly measured long-term average. Total precipitation averages around 4 mm for the month. A rainy day does not mean all-day rain.
When is the best time to visit San Francisco?
By the climate score, July, August, September and October are the strongest months for San Francisco. For a beach trip: July, August and September. September is one of them.