| 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 | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 50401 - Mason City, IA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 4 | 10 | 23 | 34 | 47 | 57 | 61 | 59 | 49 | 37 | 23 | 10 | 34 |
| Avg Max Temp (°F) | 22 | 29 | 41 | 56 | 70 | 80 | 83 | 80 | 72 | 60 | 41 | 27 | 55 |
| Avg Precip (In.) | .92 | .78 | 2.03 | 3.32 | 4.3 | 5.07 | 4.4 | 4.62 | 3.32 | 2.44 | 2.07 | 1.05 | 34.31 |