| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 5b: -15°F to -10°F |
| 2012 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 5b: -15°F to -10°F |
| 1990 Hardiness Zone: | Zone 5a: -20F to -15F |
| Average First Frost Date: | Oct. 1 - Oct. 10 |
| Average Last Frost Date: | May 21 - May 31 |
| Koppen-Geiger Climate Zone: | Dfb - Humid Continental Mild Summer, Wet All Year |
| Ecoregion: | 56d - Michigan Lake Plain |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 49405 - Custer, MI | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 14 | 15 | 22 | 33 | 43 | 52 | 57 | 56 | 48 | 39 | 30 | 20 | 36 |
| Avg Max Temp (°F) | 29 | 33 | 43 | 56 | 68 | 77 | 81 | 79 | 71 | 59 | 45 | 34 | 56 |
| Avg Precip (In.) | 2.12 | 1.42 | 2.17 | 2.82 | 2.84 | 3.21 | 2.74 | 4.01 | 3.74 | 3.43 | 3.15 | 2.38 | 34.02 |