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Helena, Montana climate
BSk Cold semi-arid
Helena has a strongly seasonal cool-temperate climate (Cold semi-arid, Köppen BSk). The hottest month is July with an average daily high near 86°F, while the coldest is January averaging around 14°F at night. Precipitation totals about 11 inches a year and is strongly seasonal — June alone averages 2.2 inches while January barely receives 0.39 inches. Winters bring significant snowfall (37 inches of snow per year on average).
Temperature & precipitation
Daily high–low temperature range with the monthly average, plus monthly precipitation split into rain and snow · 1991–2020 normals · hover a month for the exact figuresClear vs cloudy days
Share of days each month that are clear, partly cloudy or cloudy · 1991–2020 · hover a month for the day countsHelena climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°F) | 32 | 37 | 48 | 57 | 66 | 75 | 86 | 85 | 73 | 58 | 43 | 33 |
| Avg temp (°F) | 23 | 27 | 36 | 45 | 54 | 62 | 71 | 69 | 59 | 46 | 33 | 23 |
| Avg low (°F) | 14 | 17 | 25 | 32 | 42 | 49 | 55 | 53 | 45 | 34 | 23 | 14 |
| Precipitation (in) | 0.4 | 0.4 | 0.5 | 1.0 | 2.0 | 2.2 | 1.1 | 1.0 | 1.0 | 0.8 | 0.6 | 0.5 |
| Snowfall (in) | 6.6 | 6.6 | 4.6 | 2.9 | 0.1 | — | — | 0.3 | 0.2 | 2.8 | 5.4 | 7.7 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°F) | 32 | 37 | 48 | 57 | 66 | 75 |
| Avg temp (°F) | 23 | 27 | 36 | 45 | 54 | 62 |
| Avg low (°F) | 14 | 17 | 25 | 32 | 42 | 49 |
| Precipitation (in) | 0.4 | 0.4 | 0.5 | 1.0 | 2.0 | 2.2 |
| Snowfall (in) | 6.6 | 6.6 | 4.6 | 2.9 | 0.1 | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°F) | 86 | 85 | 73 | 58 | 43 | 33 |
| Avg temp (°F) | 71 | 69 | 59 | 46 | 33 | 23 |
| Avg low (°F) | 55 | 53 | 45 | 34 | 23 | 14 |
| Precipitation (in) | 1.1 | 1.0 | 1.0 | 0.8 | 0.6 | 0.5 |
| Snowfall (in) | — | 0.3 | 0.2 | 2.8 | 5.4 | 7.7 |
How often — frequency of weather events
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 7 | 7 | 7 | 9 | 11 | 12 | 7 | 6 | 6 | 7 | 7 | 7 |
| Days with high ≥ 90°F (days) | — | — | — | — | 0.3 | 2 | 12 | 11 | 2 | — | — | — |
| Days with low ≤ 32°F (days) | 29 | 26 | 25 | 15 | 3 | 0.1 | — | 0.0 | 2 | 13 | 25 | 30 |
| Days with snowfall ≥ 1 in (days) | 2 | 2 | 1 | 0.8 | — | — | — | 0.1 | 0.0 | 0.6 | 1 | 2 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 7 | 7 | 7 | 9 | 11 | 12 |
| Days with high ≥ 90°F (days) | — | — | — | — | 0.3 | 2 |
| Days with low ≤ 32°F (days) | 29 | 26 | 25 | 15 | 3 | 0.1 |
| Days with snowfall ≥ 1 in (days) | 2 | 2 | 1 | 0.8 | — | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 7 | 6 | 6 | 7 | 7 | 7 |
| Days with high ≥ 90°F (days) | 12 | 11 | 2 | — | — | — |
| Days with low ≤ 32°F (days) | — | 0.0 | 2 | 13 | 25 | 30 |
| Days with snowfall ≥ 1 in (days) | — | 0.1 | 0.0 | 0.6 | 1 | 2 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 68 | 68 | 71 | 71 | 69 | 62 | 43 | 46 | 52 | 64 | 69 | 68 |
| Clear days (≤ 30% cloud) | 3 | 3 | 3 | 2 | 3 | 4 | 12 | 10 | 10 | 6 | 3 | 3 |
| Partly cloudy days (30–70%) | 11 | 10 | 10 | 10 | 10 | 12 | 13 | 13 | 9 | 9 | 10 | 11 |
| Cloudy days (≥ 70%) | 17 | 15 | 19 | 18 | 18 | 14 | 6 | 7 | 11 | 16 | 17 | 17 |
| Relative humidity (%) | 92 | 86 | 76 | 70 | 66 | 64 | 56 | 53 | 59 | 69 | 80 | 88 |
| Wind speed (mph) | 3.2 | 3.4 | 3.6 | 3.4 | 3.0 | 2.8 | 2.4 | 2.4 | 2.6 | 2.9 | 3.0 | 3.1 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 68 | 68 | 71 | 71 | 69 | 62 |
| Clear days (≤ 30% cloud) | 3 | 3 | 3 | 2 | 3 | 4 |
| Partly cloudy days (30–70%) | 11 | 10 | 10 | 10 | 10 | 12 |
| Cloudy days (≥ 70%) | 17 | 15 | 19 | 18 | 18 | 14 |
| Relative humidity (%) | 92 | 86 | 76 | 70 | 66 | 64 |
| Wind speed (mph) | 3.2 | 3.4 | 3.6 | 3.4 | 3.0 | 2.8 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 43 | 46 | 52 | 64 | 69 | 68 |
| Clear days (≤ 30% cloud) | 12 | 10 | 10 | 6 | 3 | 3 |
| Partly cloudy days (30–70%) | 13 | 13 | 9 | 9 | 10 | 11 |
| Cloudy days (≥ 70%) | 6 | 7 | 11 | 16 | 17 | 17 |
| Relative humidity (%) | 56 | 53 | 59 | 69 | 80 | 88 |
| Wind speed (mph) | 2.4 | 2.4 | 2.6 | 2.9 | 3.0 | 3.1 |
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.
Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.