McLean, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 36.3 °F (low) to 56 °F (high). Annual precipitation averages 42.5 Inches. McLean is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 13.8 °F | 30.9 °F | 2.69 in. |
| February | 15.1 °F | 33.1 °F | 2.23 in. |
| March | 21.8 °F | 40.7 °F | 3.11 in. |
| April | 33.3 °F | 54.1 °F | 3.56 in. |
| May | 44.4 °F | 67.0 °F | 3.55 in. |
| June | 53.7 °F | 75.2 °F | 4.39 in. |
| July | 57.9 °F | 79.6 °F | 4.21 in. |
| August | 56.6 °F | 78.4 °F | 4.1 in. |
| September | 49.0 °F | 71.6 °F | 4.24 in. |
| October | 38.8 °F | 58.9 °F | 4.07 in. |
| November | 30.3 °F | 46.7 °F | 3.29 in. |
| December | 21.2 °F | 36.0 °F | 3.02 in. |
| Annual | 36.3 °F | 56 °F | 42.46 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |