Winthrop, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.1 °C (low) to 12.5 °C (high). Annual precipitation averages 1015.5 Millimeters. Winthrop is located in USDA Plant Hardiness Zone 4b. 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 | -13.3 °C | -3.7 °C | 69.34 mm |
| February | -12.4 °C | -2.1 °C | 55.88 mm |
| March | -6.6 °C | 3.3 °C | 62.74 mm |
| April | 1 °C | 11.8 °C | 84.33 mm |
| May | 7.8 °C | 19.8 °C | 84.07 mm |
| June | 13.1 °C | 24.3 °C | 104.65 mm |
| July | 15.7 °C | 26.9 °C | 100.33 mm |
| August | 14.6 °C | 25.9 °C | 88.65 mm |
| September | 10.2 °C | 21.9 °C | 98.55 mm |
| October | 4.3 °C | 14.4 °C | 108.97 mm |
| November | -1.6 °C | 7.2 °C | 82.3 mm |
| December | -8.2 °C | 0.2 °C | 75.69 mm |
| Annual | 2.1 °C | 12.5 °C | 1015.5 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4b : -31.7°C to -28.9°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |