San Francisco weather history
Wrapped in fog and hemmed by the Pacific and its bay, San Francisco enjoys one of the mildest, most even climates in America — where cool, grey summers cheerfully defy the California stereotype.
Today
26°/10°
Normal for this date 17° / 12°
Much warmer+8.2°CHow it’s changed
Right now
What it's doing today vs the historical normal for this date.
Right now
16.1°
26°10°21°12°20°11°
18°12°17°13°20°11°28°13°On this date — June 5
Warmer than usual · 8.2°C above the normal high
- Record high: 24.5° · 1949
- Record low: 9.4° · 1982
- One year ago: 16.8°
Every June 5 in history — coldest to hottest
Dots show daily highs (top) and lows (bottom) for each June 5 on record (n = 86). Outlined dots are today's forecast.
Next 24 hours
24°23°22°21°19°17°16°15°15°14°14°13°
13°
12°12°13°15°16°18°20°21°21°21°20°Last 30 days
19 of the last 24 days were warmer than the historical normal for that date. Average difference: +0.8°C.
Each bar is one day, from morning low to afternoon high. Warm-colored bars are days whose mean ran above normal; cool bars ran below. The dot inside the bar is the daily mean. The shaded band is the typical 10–90% range expected for that date. Normal = the day's mean temperature averaged across every year of record (1940–2026) for that calendar date.
Climate
What a typical year looks like — built from the full record.Climate overview
San Francisco occupies the tip of a peninsula between the Pacific Ocean and San Francisco Bay, and has one of the most distinctive climates of any large North American city. It is cool-summer Mediterranean (Köppen Csb): mild and wet in winter, dry in summer, and remarkably even in temperature year-round. The defining feature is the cold California Current and the summer fog it spawns, drawn inland through the Golden Gate, which keeps summer afternoons cool and grey while inland valleys bake. Sharp microclimates mean neighbourhoods just a few kilometres apart can differ markedly in fog and sunshine.
Rain is concentrated in the winter wet season, when 'atmospheric river' storms deliver most of the year's total, alternating with multi-year droughts. Genuine heat is rare and arrives only when offshore winds suppress the fog, as during the exceptional heat event of early September 2017.
The warmest month of the year in San Francisco is September, with a daily mean around 16.0°C and typical afternoon highs of 20.0°C. The coolest is January, when daily means drop to roughly 9.8°C and overnight lows hover around 7.5°C. Between the two extremes the climate moves through a fairly predictable seasonal cycle that you can see in the monthly chart below.
Total annual precipitation in San Francisco averages about 556 mm. The wettest month is usually January with around 106 mm of rain, while July is the driest at roughly 2 mm. The split between wet and dry seasons gives a quick sense of when umbrellas and waterproof shoes are most useful.
Over the full record (since 1940), the annual mean temperature in San Francisco has shifted by +0.7°C between the first decade and the last. The hottest single day in the record reached 35.1°C in 2017; the coldest, -2.5°C in 1990.
Monthly temperature range
September is the warmest month, January the coolest — a yearly swing of 6°C.
Each bar is the average daily low → average daily high for that month. Color shifts cool→warm by month temperature. The dot is the monthly mean. Normal = each month's value averaged across every year of record (1940–2026).
Monthly rainfall
Wettest month: January (~106 mm). Whole year averages ~556 mm of rain.
Average total millimetres of rainfall in each calendar month, across the full record.
Monthly wind
Average daily peak wind at 10 m, by month.
Monthly solar energy
Average daily incoming solar energy in megajoules per square metre — a measured proxy for how sunny the month is.
Monthly reference table
Numerical reference: average highs/lows, mean rainfall, and absolute records for each month of the year. Normal = each month's value averaged across every year of record (1940–2026).
| Month | Avg high | Avg low | Rain | Record high | Record low |
|---|---|---|---|---|---|
| January | 12.9° | 7.5° | 106 mm | 21.6° (1962) | -0.7° (1949) |
| February | 13.9° | 8.4° | 101 mm | 20.9° (1986) | -0.7° (1989) |
| March | 14.5° | 9.1° | 83 mm | 24.3° (1972) | 3.2° (1966) |
| April | 15.4° | 9.7° | 41 mm | 27.9° (2022) | 4.5° (1976) |
| May | 16.5° | 10.8° | 18 mm | 30.8° (2008) | 7.0° (1950) |
| June | 18.0° | 11.9° | 5 mm | 30.8° (2019) | 8.5° (1999) |
| July | 18.7° | 12.6° | 2 mm | 27.6° (1959) | 9.5° (1955) |
| August | 19.1° | 13.2° | 3 mm | 31.2° (1968) | 9.6° (1955) |
| September | 20.0° | 13.4° | 5 mm | 35.1° (2017) | 9.4° (1950) |
| October | 18.9° | 12.4° | 27 mm | 33.0° (1987) | 6.6° (1946) |
| November | 15.8° | 10.1° | 65 mm | 26.4° (1949) | 3.5° (1952) |
| December | 13.2° | 8.0° | 100 mm | 20.2° (2020) | -2.5° (1990) |
How it has changed
Year-by-year signals from 1940 to today.Climate stripes
Annual mean shifted from 1940–1949 to 2016–2025 by +0.7°C.
Each vertical stripe is one year. Color encodes how much that year's annual mean differed from the long-term average. Normal = each year's annual mean compared to the average of all years (1940–2026). cooler ← → warmer
Hot days vs frost days
Days ≥ 25°C per year: 4.9 early in the record → 5.1 recently. Frost days: 0 → 0.
Thin lines are raw yearly counts; thick lines are the smoothed trend that removes year-to-year noise. The hot-day threshold is auto-picked per city so the line actually moves. Normal = a centered 5-year rolling average to smooth weather noise.
Yearly hot & cold extremes
All-time high in 2017, all-time low in 1990: 35.1°C / -2.5°C.
One point per year — the single hottest and coldest day recorded that year.
Annual rainfall
~556 mm/year on average. Last decade ran +4% vs that average.
One bar per year of total rainfall. Dashed line is the long-term average. Normal = the average annual rainfall across every year of record (1940–2026).
Day-by-day grid
Each tiny square is one calendar day across the full record — ~30,000 days per city. Use the mode switch above the chart: Anomaly colors each day by how far it ran from the historical normal for that date (red = warmer, blue = cooler), Daily mean temp shows the absolute mean temperature for the day (useful to see seasons and heatwaves), and Precipitation shows daily rainfall (useful to spot wet/dry seasons and droughts). Normal = the long-term average for that calendar date (1940–2026).