| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F |
| 2012 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 5b: -15°F to -10°F |
| 1990 Hardiness Zone: | Zone 1b: -15F to -10F |
| Average First Frost Date: | Oct. 11 - Oct. 20 |
| Average Last Frost Date: | May 11 - May 20 |
| Koppen-Geiger Climate Zone: | Dfb - Humid Continental Mild Summer, Wet All Year |
| Ecoregion: | 56h - Interlobate Dead Ice Moraines |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 49240 - Grass Lake, MI | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 15 | 17 | 25 | 36 | 47 | 56 | 60 | 58 | 51 | 40 | 31 | 21 | 38 |
| Avg Max Temp (°F) | 30 | 33 | 44 | 57 | 69 | 79 | 83 | 80 | 73 | 60 | 47 | 34 | 57 |
| Avg Precip (In.) | 1.68 | 1.53 | 2.35 | 3.07 | 3.13 | 3.4 | 3.17 | 3.5 | 3.4 | 2.44 | 2.71 | 2.28 | 32.65 |