Chatham, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 38 °F (low) to 59 °F (high). Annual precipitation averages 41.8 Inches. Chatham is located in USDA Plant Hardiness Zone 6a. 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 | 15.1 °F | 33.0 °F | 2.78 in. |
| February | 16.6 °F | 36.1 °F | 2.28 in. |
| March | 24.7 °F | 44.9 °F | 2.97 in. |
| April | 35.5 °F | 58.9 °F | 3.16 in. |
| May | 46.3 °F | 70.6 °F | 3.63 in. |
| June | 55.4 °F | 78.1 °F | 4.03 in. |
| July | 60.3 °F | 82.8 °F | 3.99 in. |
| August | 58.8 °F | 81.1 °F | 3.74 in. |
| September | 50.9 °F | 73.9 °F | 4.67 in. |
| October | 39.9 °F | 61.4 °F | 4.11 in. |
| November | 30.9 °F | 49.3 °F | 2.9 in. |
| December | 22.1 °F | 38.0 °F | 3.57 in. |
| Annual | 38 °F | 59 °F | 41.83 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 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |