San Francisco records about 508mm of rain across roughly 67 wet days a year, which is a 18% chance on an average day. January is the wettest month at 114mm (22% of the annual total) and July the driest at 0mm. Local rain type: steady rain. Needed from November through March. Summer is completely dry — but bring layers for fog. The famous San Francisco fog isn't rain but can feel damp.
Chance of rain on an average day: 18%
Rainfall climatology for San Francisco. The live hour-by-hour answer for today loads at the top of this page from Open-Meteo and refreshes through the day — the figures below describe a typical year, not today.
Last updated: · Live forecast data refreshes hourly.
| Annual rainfall | 508mm |
| Rain days per year | 67 |
| Odds on an average day | 18% |
| Wettest month | January — 114mm over 15 days |
| Driest month | July — 0mm over 0 days |
| Rain type | steady rain |
| Best dry window | June through October is virtually rain-free (though foggy mornings are common in summer). |
| Worst rain window | December through February brings Pacific storms — atmospheric rivers can produce flooding. |
January delivers 11400% more rain than July (114mm vs 0mm). That gap is the difference between planning around showers and ignoring them.
22% of the year's rain falls in January alone, so San Francisco has a genuine wet season rather than evenly spread showers.
San Francisco rain typically comes as discrete showers, so a compact umbrella and a flexible plan are usually enough.
Rain falls on about 15 days in January against 0 in July — the frequency swing matters more for planning than the millimetre totals.
Climate normals. Use them to judge whether today's live forecast at the top of the page is typical or unusual for the season.
| Month | Rainfall | Rain days | Chance on a given day | Highs |
|---|---|---|---|---|
| January | 114mm | 15 | 50% | 14°C |
| February | 97mm | 13 | 43% | 14°C |
| March | 79mm | 10 | 33% | 15°C |
| April | 37mm | 5 | 17% | 17°C |
| May | 18mm | 2 | 7% | 18°C |
| June | 4mm | 1 | 3% | 20°C |
| July | 0mm | 0 | 0% | 21°C |
| August | 1mm | 1 | 3% | 21°C |
| September | 5mm | 1 | 3% | 20°C |
| October | 25mm | 3 | 10% | 18°C |
| November | 52mm | 7 | 23% | 17°C |
| December | 84mm | 11 | 37% | 15°C |
Rain probability is the chance that at least 0.2mm falls at your location — not how long it rains. For San Francisco we combine the hourly probability curve, expected volume in millimetres, and the city's own rainfall record into a single umbrella verdict.
| Factor | Weight | What it measures |
|---|---|---|
| Hourly probability | 40% | Peak and sustained chance of measurable rain across the next 24 hours. |
| Expected volume | 30% | Total millimetres, which separates a passing shower from a genuine soaking. |
| Timing & duration | 20% | When rain starts, when it eases, and the longest continuous dry window. |
| Local rain type | 10% | Drizzle, brief showers, thunderstorms or monsoon — each needs different gear. |
Live hourly values come from Open-Meteo and refresh through the day. Monthly rainfall figures are climate normals, so they describe a typical year rather than a forecast.
San Francisco records rain on roughly 67 days a year — about a 18% chance on any given day — totalling around 508mm.
January, with about 114mm over 15 rain days. That is 22% of the entire year's rainfall in a single month.
July is the driest month at 0mm across roughly 0 days. June through October is virtually rain-free (though foggy mornings are common in summer).
Needed from November through March. Summer is completely dry — but bring layers for fog. The famous San Francisco fog isn't rain but can feel damp.
No. Probability is the chance that at least 0.2mm of rain falls at your location at some point in the period. Check the expected millimetres alongside it: 40% with 0.4mm is a passing shower, 40% with 12mm is a soaking.