| 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 4b: -25F to -20F | |
| Average First Frost Date: | Oct. 1 - Oct. 10 | |
| Average Last Frost Date: | May 11 - May 20 | |
| Koppen-Geiger Climate Zone: | Dfb - Humid Continental Mild Summer, Wet All Year | |
| Ecoregion: | 54g - Rock River Hills | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 61046 - Lanark, IL | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 9 | 14 | 25 | 36 | 47 | 56 | 61 | 58 | 50 | 38 | 27 | 15 | 36 |
| Avg Max Temp (°F) | 28 | 33 | 46 | 59 | 71 | 81 | 84 | 82 | 75 | 63 | 46 | 33 | 58 |
| Avg Precip (In.) | 1.37 | 1.4 | 2.5 | 3.55 | 4.18 | 4.6 | 3.72 | 4.44 | 3.39 | 2.68 | 2.71 | 1.93 | 36.47 |