Ilion, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.7 °C (low) to 14.5 °C (high). Annual precipitation averages 1156.5 Millimeters. Ilion is located in USDA Plant Hardiness Zone 5b. 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 | -9.4 °C | -0.6 °C | 71.63 mm |
| February | -8.9 °C | 0.8 °C | 64.26 mm |
| March | -4.3 °C | 5.5 °C | 78.23 mm |
| April | 2 °C | 14 °C | 99.31 mm |
| May | 8.2 °C | 21.3 °C | 97.79 mm |
| June | 13.7 °C | 26.1 °C | 118.62 mm |
| July | 16.3 °C | 28.6 °C | 123.19 mm |
| August | 15.6 °C | 27.6 °C | 112.27 mm |
| September | 11.5 °C | 23.6 °C | 103.89 mm |
| October | 5.4 °C | 16.1 °C | 112.27 mm |
| November | 0.1 °C | 8.7 °C | 92.96 mm |
| December | -5.3 °C | 2.5 °C | 82.04 mm |
| Annual | 3.7 °C | 14.5 °C | 1156.46 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°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 |