San Francisco Weather
A month-by-month look at temperature, rainfall and what to pack in San Francisco. The annual average is 18°C high / 11°C low — hottest in September (Indian summer — best month) (22°C) and coldest in January (8°C).
San Francisco Weather at a Glance
As of 2026A quick summary of San Francisco's year-round climate and the best time to visit.
- Annual average
- 18° / 11°
- Best time to visit
- September (Indian summer — best month), October (Indian summer continues), May
- Hottest month
- September (Indian summer — best month) (22°C)
- Coldest month
- January (8°C)
- Wettest month
- January (110mm)
- Driest month
- July (peak fog) (0mm)
As of 2026, San Francisco's weather averages 18°C high / 11°C low across the year, and the best time to visit for stable temperatures, rainfall and crowds is September (Indian summer — best month), October (Indian summer continues), May. The hottest month is September (Indian summer — best month) (22°C), the coldest is January (8°C), and the wettest is January (110mm).
Best Time to Visit San Francisco
**September is the single best month to visit San Francisco.** Indian summer brings 22/14°C, 95% sunny days, fog gone, perfect light for photos. Hotels remain pricey but the weather payoff is real. Locals consider this the best month every year without exception.
October continues the Indian summer + adds spectacle: **Fleet Week** (1st week) brings US Navy Blue Angels jets ripping over the Bay (Crissy Field for best views) + ships docking at Pier 27. **Halloween in the Castro** (Oct 31) is the legendary LGBTQ+ street party. Possibly the best 2-week stretch of the year.
May is peak spring — sunny, dry, mild. **Bay to Breakers** (3rd Sunday) is SF's iconic 12-km costume race from Embarcadero to Ocean Beach with 50,000+ runners, many in elaborate costumes (or nothing at all). Hotels begin climbing toward summer peak.
San Francisco Weather Month by Month
Tap any month for a detailed guide with what to wear, sunrise/sunset and air quality.
| Month | High/Low | Rain | Rainy days | Crowds | |
|---|---|---|---|---|---|
| January | 14° / 8° | 110mm | 11 | Quiet | Details → |
| February | 15° / 9° | 110mm | 10 | Quiet | Details → |
| March | 16° / 10° | 75mm | 8 | Moderate | Details → |
| April | 17° / 11° | 35mm | 5 | Moderate | Details → |
| May | 19° / 12° | 18mm | 3 | Busy | Details → |
| June (Karl the Fog begins) | 19° / 13° | 5mm | 1 | Very busy | Details → |
| July (peak fog) | 19° / 13° | 0mm | 0 | Very busy | Details → |
| August | 20° / 14° | 0mm | 0 | Very busy | Details → |
| September (Indian summer — best month) | 22° / 14° | 8mm | 1 | Very busy | Details → |
| October (Indian summer continues) | 21° / 13° | 28mm | 3 | Very busy | Details → |
| November | 18° / 11° | 70mm | 7 | Busy | Details → |
| December (Christmas + New Year) | 14° / 8° | 110mm | 10 | Very busy | Details → |
What to Wear in San Francisco by Season
Spring — high 17°C, low 11°C. Light jacket + sweater. Cherry blossoms peak. Bring sunglasses (UV index 7).
Peak summer fog — same as June. Sweater + jacket evenings non-negotiable. Sunscreen + sunglasses for afternoons when fog burns off.
Autumn — high 21°C, low 13°C. Light jacket + sweater. Halloween costume optional in the Castro Oct 31.
Late winter — high 15°C, low 9°C. Same as January — light puffer + umbrella. Chinese New Year parade (late Feb) draws crowds for a few days.
San Francisco Weather FAQ
What is the best time to visit San Francisco? +
For weather, September (Indian summer — best month), October (Indian summer continues), May are the most comfortable months. Highs sit around 22°C with relatively stable rainfall and crowds.
What are the hottest and coldest months in San Francisco? +
The hottest month is September (Indian summer — best month) with an average high of 22°C, and the coldest is January with an average low of 8°C. The annual average is 18°C high / 11°C low.
When does it rain most in San Francisco? +
The wettest month is January (110mm over about 11 rainy days) and the driest is July (peak fog) (0mm). Total annual rainfall is roughly 569mm.
What should I pack for San Francisco? +
Spring (Mar–May) averages 17/11°C — Spring — high 17°C, low 11°C. Light jacket + sweater. Cherry blossoms peak. Bring sunglasses (UV index 7). Summer (Jun–Aug) averages 19/13°C — Peak summer fog — same as June. Sweater + jacket evenings non-negotiable. Sunscreen + sunglasses for afternoons when fog burns off. Autumn (Sep–Nov) averages 20/13°C — Autumn — high 21°C, low 13°C. Light jacket + sweater. Halloween costume optional in the Castro Oct 31. Winter (Dec–Feb) averages 14/8°C — Late winter — high 15°C, low 9°C. Same as January — light puffer + umbrella. Chinese New Year parade (late Feb) draws crowds for a few days.
What is the weather in San Francisco this month (June (Karl the Fog begins))? +
June (Karl the Fog begins) averages 19°C high / 13°C low with 5mm rainfall over about 1 rainy days. Crowds are very busy and prices are high.
Keep Planning Your San Francisco Trip
Why you can trust weather guide
Based in Chiang Mai for 8+ years, with 30+ countries visited across Southeast Asia, Japan, and Europe. Every detail in this guide is primary-source verified as of April 2026, with prices auto-refreshed via live exchange rate APIs. This isn't AI-generated boilerplate — it's written from the perspective of someone who has actually been there.