What is the hottest day ever recorded in San Francisco?

San Francisco's hottest day on record reached 106°F, set on September 1, 2017. That is the single most extreme high in the nearest long-term weather station's full daily record — about 42°F hotter than a typical year's average high of 64°F, which is why a day like it stands out as genuinely rare rather than just a hot afternoon.

What is the record high temperature in San Francisco?

The all-time record high in San Francisco is 106°F, recorded on September 1, 2017. Records are drawn from the nearest long-term weather station's full daily history, so this is the hottest single day the station has ever logged — not a typical summer peak.

What is the coldest day ever recorded in San Francisco?

San Francisco's coldest day on record bottomed out at 27°F, set on December 11, 1932. Like the record high, it comes from the station's full daily record, so it captures the most extreme cold the area has recorded rather than an average winter low.

What is the record low temperature in San Francisco?

The all-time record low in San Francisco is 27°F, recorded on December 11, 1932. The gap between that and the 106°F record high — a span of 79°F — is the full range of temperatures San Francisco has experienced across its long-term daily record.

Is it normal to be this hot in San Francisco?

It depends on how far above San Francisco's normal a given day runs. A typical year here averages a daily high near 64°F; the all-time record of 106°F (set 2017) sits about 42°F above that. When a live reading is available, the live readout just below the record high and low compares it with the temperature typical for that hour this month (estimated from the month's normal high and low), so you can see how unusual the day is rather than guessing.

When did San Francisco set its temperature records?

San Francisco's record high of 106°F was set in 2017 (September 1, 2017), and its record low of 27°F in 1932 (December 11, 1932). Both are pulled from the station's full daily record going back to 1921, so they reflect the true extremes rather than a recent or partial sample.

Has San Francisco been getting hotter?

Yes — San Francisco's annual mean temperature has trended about 1.4°F warmer since 1921 (+0.14°F per decade, fitted to the complete years of 1921–2022). That gradual shift in the average is separate from the all-time records above, which mark the single most extreme days rather than the trend, but a warming baseline is part of why recent years more often brush up against the record-high end.

San Francisco, California Weather Records

The hottest and coldest days San Francisco has ever recorded — and how today compares to normal

San Francisco’s all-time temperature records

Hottest day on record: 106°Fset September 1, 2017
Coldest day on record: 27°Fset December 11, 1932

That is a 79°F span between the hottest and coldest days San Francisco has ever recorded — the full range of what its weather has done across the station’s record back to 1921.

San Francisco, CA · Today vs. normal

2°F below typical for 4:45 AM on Sep 21

At 4:45 AM PDT on Sep 21 it was 54°F in San Francisco — 2° below the 56°F typical for that hour (estimated from the Sep 21 normal high of 70°F and low of 55°F, interpolated from the monthly normals).

How extreme San Francisco’s weather gets

San Francisco’s weather is usually mild by its own standards — a typical year averages a daily high near 64°F, and the normal high for September runs about 70°F. The records sit well outside that everyday range. The hottest day on record reached 106°F in 2017 — roughly 42°F above a typical year’s average high, the kind of gap that turns an ordinary summer into a genuine heat event.

At the other end, San Francisco has bottomed out at 27°F (1932). Those edges are why the today-versus-normal readout above is worth a glance: it shows where today falls between the normal and the record, so a hot afternoon can be judged against the real history rather than a hunch. A reading a few degrees over the September normal is ordinary; one pushing toward the 106°F record is the rare event the record marks.

Frequently asked

What is the hottest day ever recorded in San Francisco?: San Francisco's hottest day on record reached 106°F, set on September 1, 2017. That is the single most extreme high in the nearest long-term weather station's full daily record — about 42°F hotter than a typical year's average high of 64°F, which is why a day like it stands out as genuinely rare rather than just a hot afternoon.
What is the record high temperature in San Francisco?: The all-time record high in San Francisco is 106°F, recorded on September 1, 2017. Records are drawn from the nearest long-term weather station's full daily history, so this is the hottest single day the station has ever logged — not a typical summer peak.
What is the coldest day ever recorded in San Francisco?: San Francisco's coldest day on record bottomed out at 27°F, set on December 11, 1932. Like the record high, it comes from the station's full daily record, so it captures the most extreme cold the area has recorded rather than an average winter low.
What is the record low temperature in San Francisco?: The all-time record low in San Francisco is 27°F, recorded on December 11, 1932. The gap between that and the 106°F record high — a span of 79°F — is the full range of temperatures San Francisco has experienced across its long-term daily record.
Is it normal to be this hot in San Francisco?: It depends on how far above San Francisco's normal a given day runs. A typical year here averages a daily high near 64°F; the all-time record of 106°F (set 2017) sits about 42°F above that. When a live reading is available, the live readout just below the record high and low compares it with the temperature typical for that hour this month (estimated from the month's normal high and low), so you can see how unusual the day is rather than guessing.
When did San Francisco set its temperature records?: San Francisco's record high of 106°F was set in 2017 (September 1, 2017), and its record low of 27°F in 1932 (December 11, 1932). Both are pulled from the station's full daily record going back to 1921, so they reflect the true extremes rather than a recent or partial sample.
Has San Francisco been getting hotter?: Yes — San Francisco's annual mean temperature has trended about 1.4°F warmer since 1921 (+0.14°F per decade, fitted to the complete years of 1921–2022). That gradual shift in the average is separate from the all-time records above, which mark the single most extreme days rather than the trend, but a warming baseline is part of why recent years more often brush up against the record-high end.