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Janesville, Wisconsin climate
Dfa Hot-summer humid continental
Janesville has a strongly seasonal cool-temperate climate (Hot-summer humid continental, Köppen Dfa). The hottest month is July with an average daily high near 28°C, while the coldest is January averaging around −11°C at night. Around 943 mm of precipitation falls each year, peaking in June (134 mm) and easing off in January (37 mm). Winters bring significant snowfall (132 cm 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 figuresHours of sunshine per day
Estimated sunny hours each month — daylight length × clear-sky fraction · 1991–2020 monthly cloud cover (NASA POWER)Janesville climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | −3 | 0 | 6 | 14 | 21 | 26 | 28 | 27 | 23 | 15 | 7 | 0 |
| Avg temp (°C) | −7 | −5 | 1 | 8 | 15 | 20 | 22 | 21 | 17 | 10 | 3 | −4 |
| Avg low (°C) | −11 | −10 | −4 | 2 | 8 | 14 | 16 | 15 | 11 | 4 | −2 | −8 |
| Precipitation (mm) | 37 | 39 | 57 | 96 | 104 | 134 | 115 | 106 | 87 | 70 | 56 | 41 |
| Snowfall (cm) | 35 | 33 | 18 | 7 | 0 | — | — | — | — | 2 | 8 | 30 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°C) | −3 | 0 | 6 | 14 | 21 | 26 |
| Avg temp (°C) | −7 | −5 | 1 | 8 | 15 | 20 |
| Avg low (°C) | −11 | −10 | −4 | 2 | 8 | 14 |
| Precipitation (mm) | 37 | 39 | 57 | 96 | 104 | 134 |
| Snowfall (cm) | 35 | 33 | 18 | 7 | 0 | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°C) | 28 | 27 | 23 | 15 | 7 | 0 |
| Avg temp (°C) | 22 | 21 | 17 | 10 | 3 | −4 |
| Avg low (°C) | 16 | 15 | 11 | 4 | −2 | −8 |
| Precipitation (mm) | 115 | 106 | 87 | 70 | 56 | 41 |
| Snowfall (cm) | — | — | — | 2 | 8 | 30 |
How often — frequency of weather events
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 11 | 10 | 11 | 13 | 13 | 12 | 10 | 9 | 9 | 10 | 10 | 10 |
| Days with high ≥ 32°C (days) | — | — | — | — | 0.4 | 2 | 4 | 2 | 0.6 | — | — | — |
| Days with low ≤ 0°C (days) | 30 | 27 | 23 | 10 | 1 | — | — | — | 0.5 | 7 | 20 | 28 |
| Days with snowfall ≥ 2.5 cm (days) | 4 | 4 | 2 | 0.8 | 0.0 | — | — | — | — | 0.2 | 1 | 3 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 11 | 10 | 11 | 13 | 13 | 12 |
| Days with high ≥ 32°C (days) | — | — | — | — | 0.4 | 2 |
| Days with low ≤ 0°C (days) | 30 | 27 | 23 | 10 | 1 | — |
| Days with snowfall ≥ 2.5 cm (days) | 4 | 4 | 2 | 0.8 | 0.0 | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 10 | 9 | 9 | 10 | 10 | 10 |
| Days with high ≥ 32°C (days) | 4 | 2 | 0.6 | — | — | — |
| Days with low ≤ 0°C (days) | — | — | 0.5 | 7 | 20 | 28 |
| Days with snowfall ≥ 2.5 cm (days) | — | — | — | 0.2 | 1 | 3 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 65 | 63 | 64 | 66 | 66 | 60 | 52 | 53 | 52 | 63 | 66 | 66 |
| Relative humidity (%) | 90 | 87 | 80 | 77 | 77 | 77 | 76 | 75 | 75 | 77 | 82 | 89 |
| Wind speed (m/s) | 3.9 | 4.0 | 3.8 | 3.8 | 3.3 | 2.7 | 2.5 | 2.4 | 2.8 | 3.2 | 3.4 | 3.5 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 65 | 63 | 64 | 66 | 66 | 60 |
| Relative humidity (%) | 90 | 87 | 80 | 77 | 77 | 77 |
| Wind speed (m/s) | 3.9 | 4.0 | 3.8 | 3.8 | 3.3 | 2.7 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 52 | 53 | 52 | 63 | 66 | 66 |
| Relative humidity (%) | 76 | 75 | 75 | 77 | 82 | 89 |
| Wind speed (m/s) | 2.5 | 2.4 | 2.8 | 3.2 | 3.4 | 3.5 |
Methodology & sources
Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Madison Dane CO Rgnl AP (NOAA GHCN station USW00014837), about 57 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.