How extreme does Helena's weather get?

The hottest, coldest, wettest and snowiest days Helena 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 Helena Ap Asos station 4 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 Helena has recorded — each shown against what a normal day that time of year looks like.

🔥 Hottest day

105°F Jul 12, 2002

That is about 19°F hotter than a normal July afternoon in Helena (typical high near 86°F).

The three most extreme on record

1 105°F Jul 12, 2002

2 104°F Jul 13, 2002

3 104°F Jul 23, 2003

❄️ Coldest night

-42°F Feb 2, 1996

About 59°F colder than a normal February night in Helena (typical low near 17°F).

The three most extreme on record

1 -42°F Feb 2, 1996

2 -37°F Dec 24, 1983

3 -37°F Jan 30, 1996

🌧️ Most rain in one day

1.93 in May 21, 1981

About 99% of a typical May's rain in a single day (Helena averages roughly 2.0 in across the month).

The three most extreme on record

1 1.93 in May 21, 1981

2 1.82 in Aug 21, 1983

3 1.77 in Jun 18, 1979

⛄ Most snow in one day

10.4 in Nov 18, 1978

Close to a whole typical November's snow in one day (Helena averages about 5 in across the month).

The three most extreme on record

1 10.4 in Nov 18, 1978

2 10.0 in Jan 18, 2012

3 9.8 in Dec 13, 1991

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

Helena's record heat sits well above even a hot day for the season — July's 105°F is about 19°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, Helena's warmest days reach the mid-80s°F and its coldest nights drop to the mid-10s°F. But across the record it has gone as high as 105°F and as low as −42°F. A single day has delivered over 2 inches of rain or close to 10 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 Helena AP Asos (NOAA GHCN station USW00024144), about 4 km from the city centre.

How we build these numbers →

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