| 2023 Hardiness Zone: | Zone 5a: -20°F to -15°F | |
| 2012 Hardiness Zone: | Zone 5a: -20°F to -15°F | |
| 1990 Hardiness Zone: | Zone 4b: -25F to -20F | |
| Average First Frost Date: | Oct. 1 - Oct. 10 | |
| Average Last Frost Date: | May 1 - May 10 | |
| Koppen-Geiger Climate Zone: | Dfa - Humid Continental Hot Summers | |
| Ecoregion: | 47c - Iowan Surface | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 50638 - Grundy Center, IA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 6 | 12 | 24 | 35 | 47 | 58 | 62 | 59 | 49 | 38 | 25 | 12 | 35 |
| Avg Max Temp (°F) | 25 | 31 | 44 | 58 | 71 | 80 | 84 | 81 | 74 | 62 | 44 | 29 | 57 |
| Avg Precip (In.) | .91 | .99 | 2.22 | 3.27 | 4.44 | 5.1 | 4.23 | 3.97 | 3.02 | 2.55 | 2.2 | 1.22 | 34.11 |