| 2023 Hardiness Zone: | Zone 5a: -20°F to -15°F Zone 5b: -15°F to -10°F | |
| 2012 Hardiness Zone: | Zone 5a: -20°F to -15°F | |
| 1990 Hardiness Zone: | Zone 5a: -20F to -15F | |
| Average First Frost Date: | Oct. 11 - Oct. 20 | |
| Average Last Frost Date: | May 1 - May 10 | |
| Koppen-Geiger Climate Zone: | Dfa - Humid Continental Hot Summers | |
| Ecoregion: | 47e - Steeply Rolling Loess Prairies | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | 1 - 7 days Over 86°F |
Annual Climate Data for ZIP Code 51442 - Denison, IA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 8 | 14 | 25 | 36 | 49 | 59 | 64 | 61 | 51 | 39 | 25 | 13 | 37 |
| Avg Max Temp (°F) | 27 | 33 | 46 | 59 | 71 | 81 | 84 | 82 | 75 | 62 | 44 | 31 | 58 |
| Avg Precip (In.) | .8 | .77 | 2.16 | 3.09 | 4.19 | 4.33 | 3.89 | 3.42 | 3.3 | 2.32 | 1.6 | .99 | 30.86 |