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Ottumwa, Iowa climate
Dfa Hot-summer humid continental
Ottumwa has a strongly seasonal cool-temperate climate (Hot-summer humid continental, Köppen Dfa). The hottest month is July with an average daily high near 30°C, while the coldest is January averaging around −10°C at night. Precipitation totals about 939 mm a year and is strongly seasonal — June alone averages 137 mm while January barely receives 26 mm. Light snow accumulates each winter (60 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 countsOttumwa climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 0 | 3 | 10 | 17 | 23 | 28 | 30 | 29 | 25 | 18 | 10 | 3 |
| Avg temp (°C) | −5 | −3 | 4 | 11 | 17 | 22 | 24 | 23 | 19 | 12 | 4 | −2 |
| Avg low (°C) | −10 | −8 | −2 | 4 | 11 | 16 | 18 | 17 | 12 | 5 | −1 | −7 |
| Precipitation (mm) | 26 | 36 | 57 | 95 | 128 | 137 | 98 | 113 | 89 | 71 | 53 | 37 |
| Snowfall (cm) | 18 | 15 | 8 | 4 | — | — | — | — | — | 1 | 4 | 11 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°C) | 0 | 3 | 10 | 17 | 23 | 28 |
| Avg temp (°C) | −5 | −3 | 4 | 11 | 17 | 22 |
| Avg low (°C) | −10 | −8 | −2 | 4 | 11 | 16 |
| Precipitation (mm) | 26 | 36 | 57 | 95 | 128 | 137 |
| Snowfall (cm) | 18 | 15 | 8 | 4 | — | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°C) | 30 | 29 | 25 | 18 | 10 | 3 |
| Avg temp (°C) | 24 | 23 | 19 | 12 | 4 | −2 |
| Avg low (°C) | 18 | 17 | 12 | 5 | −1 | −7 |
| Precipitation (mm) | 98 | 113 | 89 | 71 | 53 | 37 |
| Snowfall (cm) | — | — | — | 1 | 4 | 11 |
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 | 10 | 12 | 13 | 11 | 9 | 9 | 8 | 8 | 8 | 7 |
| Days with high ≥ 32°C (days) | — | — | — | — | 0.6 | 4 | 8 | 5 | 2 | 0.1 | — | — |
| Days with low ≤ 0°C (days) | 29 | 25 | 20 | 6 | 0.4 | — | — | — | 0.2 | 5 | 18 | 27 |
| Days with snowfall ≥ 2.5 cm (days) | 1 | 0.6 | 0.4 | 0.1 | — | 0.0 | — | — | — | 0.0 | 0.3 | 0.5 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 7 | 7 | 10 | 12 | 13 | 11 |
| Days with high ≥ 32°C (days) | — | — | — | — | 0.6 | 4 |
| Days with low ≤ 0°C (days) | 29 | 25 | 20 | 6 | 0.4 | — |
| Days with snowfall ≥ 2.5 cm (days) | 1 | 0.6 | 0.4 | 0.1 | — | 0.0 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 9 | 9 | 8 | 8 | 8 | 7 |
| Days with high ≥ 32°C (days) | 8 | 5 | 2 | 0.1 | — | — |
| Days with low ≤ 0°C (days) | — | — | 0.2 | 5 | 18 | 27 |
| Days with snowfall ≥ 2.5 cm (days) | — | — | — | 0.0 | 0.3 | 0.5 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 65 | 65 | 65 | 65 | 65 | 58 | 49 | 50 | 47 | 57 | 62 | 65 |
| Clear days (≤ 30% cloud) | 5 | 4 | 5 | 6 | 5 | 7 | 10 | 10 | 12 | 8 | 6 | 5 |
| Partly cloudy days (30–70%) | 11 | 10 | 11 | 9 | 10 | 11 | 13 | 12 | 10 | 9 | 10 | 11 |
| Cloudy days (≥ 70%) | 15 | 14 | 16 | 16 | 16 | 13 | 9 | 9 | 9 | 14 | 14 | 15 |
| Relative humidity (%) | 85 | 81 | 76 | 73 | 75 | 76 | 73 | 71 | 70 | 73 | 79 | 85 |
| Wind speed (mph) | 8.3 | 8.4 | 8.5 | 8.3 | 6.9 | 5.9 | 5.2 | 5.0 | 5.8 | 6.8 | 7.4 | 7.4 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 65 | 65 | 65 | 65 | 65 | 58 |
| Clear days (≤ 30% cloud) | 5 | 4 | 5 | 6 | 5 | 7 |
| Partly cloudy days (30–70%) | 11 | 10 | 11 | 9 | 10 | 11 |
| Cloudy days (≥ 70%) | 15 | 14 | 16 | 16 | 16 | 13 |
| Relative humidity (%) | 85 | 81 | 76 | 73 | 75 | 76 |
| Wind speed (mph) | 8.3 | 8.4 | 8.5 | 8.3 | 6.9 | 5.9 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 49 | 50 | 47 | 57 | 62 | 65 |
| Clear days (≤ 30% cloud) | 10 | 10 | 12 | 8 | 6 | 5 |
| Partly cloudy days (30–70%) | 13 | 12 | 10 | 9 | 10 | 11 |
| Cloudy days (≥ 70%) | 9 | 9 | 9 | 14 | 14 | 15 |
| Relative humidity (%) | 73 | 71 | 70 | 73 | 79 | 85 |
| Wind speed (mph) | 5.2 | 5.0 | 5.8 | 6.8 | 7.4 | 7.4 |
Methodology & sources
Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Ottumwa Ind AP (NOAA GHCN station USW00014950), about 9 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.