How extreme does Boulder's weather get?

The hottest, coldest, wettest and snowiest days Boulder 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 Longmont 2 Ese station 24 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 Boulder has recorded — each shown against what a normal day that time of year looks like.

🔥 Hottest day

106°F Jul 7, 1973

That is about 15°F hotter than a normal July afternoon in Boulder (typical high near 91°F).

The three most extreme on record

1 106°F Jul 7, 1973

2 106°F Jun 27, 1994

3 105°F Jul 30, 1980

❄️ Coldest night

-31°F Dec 22, 1990

About 46°F colder than a normal December night in Boulder (typical low near 15°F).

The three most extreme on record

1 -31°F Dec 22, 1990

2 -30°F Jan 18, 1984

3 -28°F Feb 5, 1989

🌧️ Most rain in one day

2.53 in May 6, 1978

More rain in a single day than Boulder usually gets in the whole month of May (typical May total about 2.0 in).

The three most extreme on record

1 2.53 in May 6, 1978

2 2.38 in Jun 6, 1972

3 2.29 in Jun 7, 1997

⛄ Most snow in one day

27.0 in Dec 25, 1982

The three most extreme on record

1 27.0 in Dec 25, 1982

2 19.0 in Dec 28, 1987

3 13.0 in Dec 28, 1979

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.

normal range of daily temperatureshottest ever recordedcoldest ever recorded

Boulder's record heat sits well above even a hot day for the season — July's 106°F is about 15°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, Boulder's warmest days reach the low 90s°F and its coldest nights drop to the mid-10s°F. But across the record it has gone as high as 106°F and as low as −31°F. A single day has delivered over 3 inches of rain or close to 27 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 Brighton 3 SE (NOAA GHCN station USC00050950), about 38 km from the city centre.

How we build these numbers →

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