Hartford, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.4 °C (low) to 14.4 °C (high). Annual precipitation averages 1042.4 Millimeters. Hartford is located in USDA Plant Hardiness Zone 5a. 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 | -11.6 °C | -0.7 °C | 66.8 mm |
| February | -11.1 °C | 1.2 °C | 54.86 mm |
| March | -5.6 °C | 6.1 °C | 68.58 mm |
| April | 1.4 °C | 14.2 °C | 82.04 mm |
| May | 7.6 °C | 21 °C | 88.39 mm |
| June | 12.7 °C | 25.5 °C | 116.59 mm |
| July | 15.3 °C | 28.1 °C | 107.19 mm |
| August | 14.4 °C | 27.1 °C | 105.92 mm |
| September | 10.1 °C | 23 °C | 87.12 mm |
| October | 3.9 °C | 15.8 °C | 100.84 mm |
| November | -1.5 °C | 8.7 °C | 81.53 mm |
| December | -6.6 °C | 2.3 °C | 82.55 mm |
| Annual | 2.4 °C | 14.4 °C | 1042.41 mm |
| 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 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |