Portville, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 35.3 °F (low) to 57.1 °F (high). Annual precipitation averages 42 Inches. Portville is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 14.6 °F | 31.8 °F | 2.89 in. |
| February | 15.1 °F | 34.3 °F | 2.11 in. |
| March | 21.3 °F | 43.1 °F | 2.79 in. |
| April | 31.7 °F | 56.2 °F | 3.51 in. |
| May | 42.7 °F | 68.9 °F | 3.74 in. |
| June | 51.5 °F | 76.7 °F | 4.45 in. |
| July | 55.8 °F | 80.2 °F | 4.37 in. |
| August | 55.0 °F | 78.5 °F | 4.14 in. |
| September | 48.1 °F | 71.9 °F | 3.93 in. |
| October | 37.4 °F | 59.6 °F | 3.79 in. |
| November | 28.7 °F | 47.1 °F | 3.05 in. |
| December | 21.1 °F | 36.4 °F | 3.19 in. |
| Annual | 35.3 °F | 57.1 °F | 41.96 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |