| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | 14.6° | 8.5° | 114.8mm | 11.4 | 60 |
| February | 15.9° | 8.9° | 104.3mm | 10.1 | 67 |
| March | 16.7° | 9.3° | 79.7mm | 10.7 | 68 |
| April | 17.2° | 9.8° | 40.4mm | 6.7 | 78 |
| May | 17.9° | 10.7° | 17.5mm | 3.7 | 86 |
| June | 19.2° | 11.8° | 4.5mm | 1.5 | 94 |
| July | 19.2° | 12.5° | 0.4mm | 0.9 | 96 |
| August | 20.1° | 13.2° | 1.1mm | 1.1 | 98 |
| September | 21.4° | 13.3° | 2.9mm | 1.4 | 97 |
| October | 21° | 12.6° | 26.5mm | 3.6 | 93 |
| November | 17.7° | 10.6° | 62.1mm | 8 | 77 |
| December | 14.7° | 8.7° | 135.3mm | 12 | 59 |
January in San Francisco averages a daily high of 14.6°C with nights around 8.5°C. Expect roughly 11.4 wet days totalling 114.8mm. Generally workable, with some weather to plan around.
February in San Francisco averages a daily high of 15.9°C with nights around 8.9°C. Expect roughly 10.1 wet days totalling 104.3mm. Generally workable, with some weather to plan around.
March in San Francisco averages a daily high of 16.7°C with nights around 9.3°C. Expect roughly 10.7 wet days totalling 79.7mm. Generally workable, with some weather to plan around.
April in San Francisco averages a daily high of 17.2°C with nights around 9.8°C. Expect roughly 6.7 wet days totalling 40.4mm. Comfortable conditions for being outdoors all day.
May in San Francisco averages a daily high of 17.9°C with nights around 10.7°C. Expect roughly 3.7 wet days totalling 17.5mm. Comfortable conditions for being outdoors all day.
June in San Francisco averages a daily high of 19.2°C with nights around 11.8°C. Rain is rare — about 1.5 wet days and 4.5mm across the month. Comfortable conditions for being outdoors all day.
July in San Francisco averages a daily high of 19.2°C with nights around 12.5°C. Rain is rare — about 0.9 wet days and 0.4mm across the month. Comfortable conditions for being outdoors all day.
August in San Francisco averages a daily high of 20.1°C with nights around 13.2°C. Rain is rare — about 1.1 wet days and 1.1mm across the month. Comfortable conditions for being outdoors all day.
September in San Francisco averages a daily high of 21.4°C with nights around 13.3°C. Rain is rare — about 1.4 wet days and 2.9mm across the month. Comfortable conditions for being outdoors all day.
October in San Francisco averages a daily high of 21°C with nights around 12.6°C. Expect roughly 3.6 wet days totalling 26.5mm. Comfortable conditions for being outdoors all day.
November in San Francisco averages a daily high of 17.7°C with nights around 10.6°C. Expect roughly 8 wet days totalling 62.1mm. Comfortable conditions for being outdoors all day.
December in San Francisco averages a daily high of 14.7°C with nights around 8.7°C. Expect roughly 12 wet days totalling 135.3mm. Generally workable, with some weather to plan around.
Each month scores out of 100. It starts at 100 and loses points for daytime highs outside a 20–27°C band, for wet days, and for nights below 2°C. Nothing else is weighted in — no crowd data, no prices, no opinion. San Francisco peaks at 98.
Based on 30 years of records, June–October scores highest for comfort in San Francisco, balancing daytime temperature against rainfall.
September is the warmest, averaging a daily high of 21.4°C.
December is the wettest, averaging 135.3mm of rain across roughly 12 wet days.
January is the coolest month, with average daily highs around 14.6°C.