| 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: | 47f - Rolling Loess Prairies |
| Heat Zone Days: | 1 - 7 days Over 86°F |
Annual Climate Data for ZIP Code 52314 - Mount Vernon, IA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 10 | 16 | 27 | 38 | 49 | 59 | 63 | 61 | 52 | 41 | 28 | 16 | 38 |
| Avg Max Temp (°F) | 27 | 34 | 46 | 61 | 72 | 81 | 85 | 83 | 75 | 63 | 46 | 32 | 59 |
| Avg Precip (In.) | 1.14 | 1.18 | 2.26 | 3.45 | 4.27 | 4.63 | 4.19 | 4.57 | 3.55 | 2.53 | 2.46 | 1.56 | 35.79 |