| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 5b: -15°F to -10°F | |
| 2012 Hardiness Zone: | Zone 5b: -15°F to -10°F | |
| 1990 Hardiness Zone: | Zone 5a: -20F to -15F | |
| Average First Frost Date: | Oct. 11 - Oct. 20 | |
| Average Last Frost Date: | Apr. 21 - Apr. 30 | |
| Koppen-Geiger Climate Zone: | Dfa - Humid Continental Hot Summers | |
| Ecoregion: | 40a - Loess Flats and Till Plains | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | 8 - 14 days Over 86°F |
Annual Climate Data for ZIP Code 52501 - Ottumwa, IA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 13 | 18 | 29 | 40 | 52 | 61 | 66 | 64 | 54 | 43 | 30 | 18 | 41 |
| Avg Max Temp (°F) | 31 | 37 | 49 | 62 | 73 | 82 | 87 | 85 | 77 | 65 | 48 | 35 | 61 |
| Avg Precip (In.) | 1.07 | 1.17 | 2.35 | 3.41 | 4.57 | 4.34 | 4.55 | 4.04 | 3.98 | 2.77 | 2.56 | 1.43 | 36.24 |