| 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 11 - May 20 |
| Koppen-Geiger Climate Zone: | Dfa - Humid Continental Hot Summers |
| Ecoregion: | 47c - Iowan Surface |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 52310 - Monticello, IA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 7 | 13 | 25 | 36 | 48 | 57 | 62 | 59 | 50 | 39 | 27 | 14 | 37 |
| Avg Max Temp (°F) | 26 | 32 | 45 | 59 | 71 | 80 | 84 | 82 | 74 | 62 | 45 | 31 | 58 |
| Avg Precip (In.) | 1.16 | 1.19 | 2.25 | 3.28 | 3.9 | 4.54 | 3.71 | 4.61 | 3.46 | 2.44 | 2.47 | 1.51 | 34.53 |