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Lewiston, Idaho climate
Csb Warm-summer Mediterranean
Lewiston has a seasonal cool-temperate climate (Warm-summer Mediterranean, Köppen Csb). The hottest month is August with an average daily high near 86°F, while the coldest is December averaging around 22°F at night. Precipitation totals about 28 inches a year and is strongly seasonal — November alone averages 3.5 inches while July barely receives 0.66 inches. Winters bring significant snowfall (51 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 countsLewiston climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°F) | 37 | 42 | 50 | 58 | 67 | 73 | 84 | 86 | 76 | 61 | 45 | 36 |
| Avg temp (°F) | 30 | 33 | 39 | 45 | 53 | 58 | 65 | 65 | 58 | 47 | 36 | 29 |
| Avg low (°F) | 22 | 24 | 28 | 32 | 38 | 42 | 45 | 45 | 40 | 33 | 27 | 22 |
| Precipitation (in) | 3.3 | 2.6 | 3.1 | 2.8 | 2.6 | 1.7 | 0.7 | 0.7 | 1.0 | 2.4 | 3.5 | 3.5 |
| Snowfall (in) | 14.5 | 8.6 | 4.9 | 1.0 | 0.2 | — | — | — | — | 0.2 | 6.0 | 15.5 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°F) | 37 | 42 | 50 | 58 | 67 | 73 |
| Avg temp (°F) | 30 | 33 | 39 | 45 | 53 | 58 |
| Avg low (°F) | 22 | 24 | 28 | 32 | 38 | 42 |
| Precipitation (in) | 3.3 | 2.6 | 3.1 | 2.8 | 2.6 | 1.7 |
| Snowfall (in) | 14.5 | 8.6 | 4.9 | 1.0 | 0.2 | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°F) | 84 | 86 | 76 | 61 | 45 | 36 |
| Avg temp (°F) | 65 | 65 | 58 | 47 | 36 | 29 |
| Avg low (°F) | 45 | 45 | 40 | 33 | 27 | 22 |
| Precipitation (in) | 0.7 | 0.7 | 1.0 | 2.4 | 3.5 | 3.5 |
| Snowfall (in) | — | — | — | 0.2 | 6.0 | 15.5 |
How often — frequency of weather events
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 16 | 14 | 16 | 13 | 11 | 9 | 4 | 4 | 6 | 11 | 16 | 16 |
| Days with high ≥ 90°F (days) | — | — | — | — | 0.3 | 0.9 | 9 | 11 | 2 | — | — | — |
| Days with low ≤ 32°F (days) | 25 | 21 | 19 | 11 | 4 | 0.3 | 0.1 | 0.0 | 3 | 10 | 18 | 27 |
| Days with snowfall ≥ 1 in (days) | 5 | 3 | 2 | 0.3 | 0.1 | — | — | — | — | 0.1 | 2 | 6 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 16 | 14 | 16 | 13 | 11 | 9 |
| Days with high ≥ 90°F (days) | — | — | — | — | 0.3 | 0.9 |
| Days with low ≤ 32°F (days) | 25 | 21 | 19 | 11 | 4 | 0.3 |
| Days with snowfall ≥ 1 in (days) | 5 | 3 | 2 | 0.3 | 0.1 | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 4 | 4 | 6 | 11 | 16 | 16 |
| Days with high ≥ 90°F (days) | 9 | 11 | 2 | — | — | — |
| Days with low ≤ 32°F (days) | 0.1 | 0.0 | 3 | 10 | 18 | 27 |
| Days with snowfall ≥ 1 in (days) | — | — | — | 0.1 | 2 | 6 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 74 | 70 | 71 | 68 | 62 | 56 | 33 | 36 | 44 | 60 | 72 | 74 |
| Clear days (≤ 30% cloud) | 2 | 4 | 4 | 4 | 6 | 8 | 17 | 16 | 13 | 8 | 3 | 2 |
| Partly cloudy days (30–70%) | 9 | 8 | 8 | 9 | 10 | 10 | 10 | 10 | 9 | 8 | 9 | 9 |
| Cloudy days (≥ 70%) | 20 | 17 | 19 | 17 | 15 | 12 | 5 | 5 | 9 | 15 | 19 | 20 |
| Relative humidity (%) | 89 | 83 | 76 | 70 | 66 | 62 | 52 | 47 | 51 | 64 | 79 | 88 |
| Wind speed (mph) | 4.0 | 4.2 | 4.4 | 4.5 | 4.2 | 4.3 | 3.9 | 3.7 | 3.7 | 3.9 | 4.0 | 4.0 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 74 | 70 | 71 | 68 | 62 | 56 |
| Clear days (≤ 30% cloud) | 2 | 4 | 4 | 4 | 6 | 8 |
| Partly cloudy days (30–70%) | 9 | 8 | 8 | 9 | 10 | 10 |
| Cloudy days (≥ 70%) | 20 | 17 | 19 | 17 | 15 | 12 |
| Relative humidity (%) | 89 | 83 | 76 | 70 | 66 | 62 |
| Wind speed (mph) | 4.0 | 4.2 | 4.4 | 4.5 | 4.2 | 4.3 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 33 | 36 | 44 | 60 | 72 | 74 |
| Clear days (≤ 30% cloud) | 17 | 16 | 13 | 8 | 3 | 2 |
| Partly cloudy days (30–70%) | 10 | 10 | 9 | 8 | 9 | 9 |
| Cloudy days (≥ 70%) | 5 | 5 | 9 | 15 | 19 | 20 |
| Relative humidity (%) | 52 | 47 | 51 | 64 | 79 | 88 |
| Wind speed (mph) | 3.9 | 3.7 | 3.7 | 3.9 | 4.0 | 4.0 |
Methodology & sources
Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Moscow U OF I (NOAA GHCN station USC00106152), about 35 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.