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Marshalltown, Iowa climate
Dfa Hot-summer humid continental
Marshalltown 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 −12°C at night. Precipitation totals about 922 mm a year and is strongly seasonal — June alone averages 145 mm while January barely receives 28 mm. Winters bring significant snowfall (99 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 figuresClear vs cloudy days
Share of days each month that are clear, partly cloudy or cloudy · 1991–2020 · hover a month for the day countsMarshalltown climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | −2 | 0 | 8 | 16 | 23 | 28 | 29 | 28 | 25 | 17 | 8 | 1 |
| Avg temp (°C) | −7 | −5 | 3 | 10 | 16 | 22 | 24 | 22 | 18 | 11 | 3 | −4 |
| Avg low (°C) | −12 | −9 | −3 | 3 | 10 | 16 | 18 | 16 | 11 | 5 | −2 | −8 |
| Precipitation (mm) | 28 | 29 | 50 | 103 | 117 | 145 | 110 | 106 | 80 | 70 | 47 | 37 |
| Snowfall (cm) | 26 | 24 | 12 | 4 | 0 | — | — | — | — | 1 | 8 | 25 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°C) | −2 | 0 | 8 | 16 | 23 | 28 |
| Avg temp (°C) | −7 | −5 | 3 | 10 | 16 | 22 |
| Avg low (°C) | −12 | −9 | −3 | 3 | 10 | 16 |
| Precipitation (mm) | 28 | 29 | 50 | 103 | 117 | 145 |
| Snowfall (cm) | 26 | 24 | 12 | 4 | 0 | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°C) | 29 | 28 | 25 | 17 | 8 | 1 |
| Avg temp (°C) | 24 | 22 | 18 | 11 | 3 | −4 |
| Avg low (°C) | 18 | 16 | 11 | 5 | −2 | −8 |
| Precipitation (mm) | 110 | 106 | 80 | 70 | 47 | 37 |
| Snowfall (cm) | — | — | — | 1 | 8 | 25 |
How often — frequency of weather events
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 8 | 8 | 10 | 11 | 13 | 12 | 9 | 9 | 9 | 9 | 8 | 8 |
| Days with high ≥ 32°C (days) | — | — | — | 0.1 | 0.8 | 4 | 6 | 3 | 2 | 0.1 | — | — |
| Days with low ≤ 0°C (days) | 30 | 27 | 23 | 10 | 1 | — | — | — | 0.6 | 9 | 22 | 29 |
| Days with snowfall ≥ 2.5 cm (days) | 3 | 3 | 1 | 0.5 | 0.0 | — | — | — | — | 0.1 | 1 | 3 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 8 | 8 | 10 | 11 | 13 | 12 |
| Days with high ≥ 32°C (days) | — | — | — | 0.1 | 0.8 | 4 |
| Days with low ≤ 0°C (days) | 30 | 27 | 23 | 10 | 1 | — |
| Days with snowfall ≥ 2.5 cm (days) | 3 | 3 | 1 | 0.5 | 0.0 | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 9 | 9 | 9 | 9 | 8 | 8 |
| Days with high ≥ 32°C (days) | 6 | 3 | 2 | 0.1 | — | — |
| Days with low ≤ 0°C (days) | — | — | 0.6 | 9 | 22 | 29 |
| Days with snowfall ≥ 2.5 cm (days) | — | — | — | 0.1 | 1 | 3 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 64 | 63 | 65 | 65 | 66 | 59 | 50 | 51 | 49 | 59 | 64 | 65 |
| Clear days (≤ 30% cloud) | 5 | 5 | 5 | 6 | 5 | 6 | 9 | 9 | 11 | 8 | 5 | 4 |
| Partly cloudy days (30–70%) | 11 | 11 | 10 | 9 | 10 | 11 | 12 | 11 | 10 | 9 | 10 | 11 |
| Cloudy days (≥ 70%) | 15 | 13 | 16 | 16 | 16 | 13 | 10 | 11 | 10 | 15 | 15 | 15 |
| Relative humidity (%) | 88 | 84 | 78 | 74 | 75 | 77 | 76 | 74 | 72 | 74 | 80 | 87 |
| Wind speed (mph) | 8.7 | 8.7 | 8.8 | 9.0 | 7.7 | 6.2 | 5.3 | 5.1 | 6.2 | 7.2 | 7.9 | 8.0 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 64 | 63 | 65 | 65 | 66 | 59 |
| Clear days (≤ 30% cloud) | 5 | 5 | 5 | 6 | 5 | 6 |
| Partly cloudy days (30–70%) | 11 | 11 | 10 | 9 | 10 | 11 |
| Cloudy days (≥ 70%) | 15 | 13 | 16 | 16 | 16 | 13 |
| Relative humidity (%) | 88 | 84 | 78 | 74 | 75 | 77 |
| Wind speed (mph) | 8.7 | 8.7 | 8.8 | 9.0 | 7.7 | 6.2 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 50 | 51 | 49 | 59 | 64 | 65 |
| Clear days (≤ 30% cloud) | 9 | 9 | 11 | 8 | 5 | 4 |
| Partly cloudy days (30–70%) | 12 | 11 | 10 | 9 | 10 | 11 |
| Cloudy days (≥ 70%) | 10 | 11 | 10 | 15 | 15 | 15 |
| Relative humidity (%) | 76 | 74 | 72 | 74 | 80 | 87 |
| Wind speed (mph) | 5.3 | 5.1 | 6.2 | 7.2 | 7.9 | 8.0 |
Methodology & sources
Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Waterloo Muni AP (NOAA GHCN station USW00094910), about 70 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.