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Mason City, Iowa climate
Dfa Hot-summer humid continental
Mason City has a strongly seasonal cool-temperate climate (Hot-summer humid continental, Köppen Dfa). The hottest month is July with an average daily high near 29°C, while the coldest is January averaging around −13°C at night. Precipitation totals about 924 mm a year and is strongly seasonal — June alone averages 137 mm while January barely receives 20 mm.
Temperature & precipitation
Daily high–low temperature range with the monthly average, plus monthly precipitation · 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)Mason City climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | −4 | −1 | 6 | 15 | 22 | 27 | 29 | 27 | 24 | 16 | 7 | −1 |
| Avg temp (°C) | −8 | −6 | 1 | 9 | 15 | 21 | 23 | 21 | 17 | 10 | 2 | −5 |
| Avg low (°C) | −13 | −11 | −4 | 2 | 9 | 15 | 16 | 15 | 10 | 4 | −3 | −10 |
| Precipitation (mm) | 20 | 23 | 53 | 105 | 136 | 137 | 120 | 102 | 93 | 65 | 43 | 26 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°C) | −4 | −1 | 6 | 15 | 22 | 27 |
| Avg temp (°C) | −8 | −6 | 1 | 9 | 15 | 21 |
| Avg low (°C) | −13 | −11 | −4 | 2 | 9 | 15 |
| Precipitation (mm) | 20 | 23 | 53 | 105 | 136 | 137 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°C) | 29 | 27 | 24 | 16 | 7 | −1 |
| Avg temp (°C) | 23 | 21 | 17 | 10 | 2 | −5 |
| Avg low (°C) | 16 | 15 | 10 | 4 | −3 | −10 |
| Precipitation (mm) | 120 | 102 | 93 | 65 | 43 | 26 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 64 | 62 | 67 | 65 | 65 | 60 | 50 | 51 | 50 | 60 | 64 | 66 |
| Relative humidity (%) | 88 | 85 | 78 | 74 | 75 | 77 | 77 | 76 | 73 | 74 | 81 | 87 |
| Wind speed (mph) | 9.1 | 9.0 | 9.1 | 9.3 | 8.0 | 6.5 | 5.5 | 5.2 | 6.4 | 7.4 | 8.1 | 8.4 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 64 | 62 | 67 | 65 | 65 | 60 |
| Relative humidity (%) | 88 | 85 | 78 | 74 | 75 | 77 |
| Wind speed (mph) | 9.1 | 9.0 | 9.1 | 9.3 | 8.0 | 6.5 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 50 | 51 | 50 | 60 | 64 | 66 |
| Relative humidity (%) | 77 | 76 | 73 | 74 | 81 | 87 |
| Wind speed (mph) | 5.5 | 5.2 | 6.4 | 7.4 | 8.1 | 8.4 |
Methodology & sources
Temperature & precipitation — 1991–2020 normals computed from 30 years of daily observations at Mason City Municipal Arpt, a weather station, about 10 km from the city centre. The underlying daily records come from NOAA's global station network.
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.