Harriman, New York has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.8 °C (low) to 15.9 °C (high). Annual precipitation averages 1257.5 Millimeters. Harriman is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7.6 °C | 1.9 °C | 91.69 mm |
| February | -6.6 °C | 3.8 °C | 70.1 mm |
| March | -2.4 °C | 8.2 °C | 104.9 mm |
| April | 3.7 °C | 15.7 °C | 98.55 mm |
| May | 9.2 °C | 21.5 °C | 94.23 mm |
| June | 14.3 °C | 26.1 °C | 119.63 mm |
| July | 16.9 °C | 28.9 °C | 112.27 mm |
| August | 16.2 °C | 28 °C | 122.43 mm |
| September | 11.9 °C | 24.1 °C | 119.63 mm |
| October | 5.6 °C | 17.4 °C | 118.11 mm |
| November | 0.5 °C | 10.8 °C | 99.31 mm |
| December | -4.1 °C | 4.8 °C | 106.68 mm |
| Annual | 4.8 °C | 15.9 °C | 1257.53 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |