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Weather extremes

How extreme does San Luis Obispo's weather get?

The hottest, coldest, wettest and snowiest days San Luis Obispo has recorded — the outer limits of what its weather can do, and how far they sit beyond a normal day.

Based on 50+ years of daily weather observations (1971–present), from the Paso Robles station 38 km away. Updated through May 2026 — an all-time extreme only changes when a more extreme day actually occurs, so some dates are old. That is normal, not stale data.

The four kinds of extreme

The hottest, coldest, wettest and snowiest single days San Luis Obispo has recorded — each shown against what a normal day that time of year looks like.

🔥 Hottest day
115°F Sep 7, 2020

That is about 26°F hotter than a normal September afternoon in San Luis Obispo (typical high near 89°F).

The three most extreme on record

1 115°F Sep 7, 2020
2 114°F Jul 23, 2006
3 114°F Sep 3, 2017
❄️ Coldest night
7°F Dec 22, 1990

About 26°F colder than a normal December night in San Luis Obispo (typical low near 33°F).

The three most extreme on record

1 7°F Dec 22, 1990
2 7°F Dec 24, 1990
3 8°F Dec 23, 1990
🌧️ Most rain in one day
5.11 in Oct 31, 2004

More rain in a single day than San Luis Obispo usually gets in the whole month of October (typical October total about 0.7 in).

The three most extreme on record

1 5.11 in Oct 31, 2004
2 4.70 in Mar 10, 1995
3 3.88 in Oct 14, 2009
Most snow in one day
4.0 in Dec 15, 1988

Top recorded days

1 4.0 in Dec 15, 1988

How hot and cold it gets, month by month

The shaded band is the normal range of daily temperatures for each month. The dots show the most extreme it has ever been — so you can see how far beyond a normal day the records really sit.

-10°10°30°50°70°90°110°130° all-time high 115°F JanFebMarAprMayJunJulAugSepOctNovDec
normal range of daily temperatureshottest ever recordedcoldest ever recorded

San Luis Obispo's record heat sits well above even a hot day for the season — September's 115°F is about 26°F beyond a normal hot afternoon. Its record cold is just as far below a normal winter night — the dots mark how rare each extreme really is.

In plain terms

In a normal year, San Luis Obispo's warmest days reach the low 90s°F and its coldest nights drop to the low 30s°F. But across the record it has gone as high as 115°F and as low as 7°F. A single day has delivered over 5 inches of rain or close to 4 inches of snow. Those are the outer edges worth knowing if you are moving here, planning a trip, or thinking about a house.
Methodology & sources

Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Santa Maria Public AP (NOAA GHCN station USW00023273), about 47 km from the city centre.

How we build these numbers →