Marathon, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.7 °C (low) to 13.8 °C (high). Annual precipitation averages 1141.2 Millimeters. Marathon is located in USDA Plant Hardiness Zone 5b. 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 | -9.6 °C | -0.2 °C | 76.2 mm |
| February | -9.2 °C | 0.9 °C | 71.37 mm |
| March | -5.3 °C | 5.3 °C | 83.57 mm |
| April | 1.1 °C | 13 °C | 99.06 mm |
| May | 7.2 °C | 19.9 °C | 99.82 mm |
| June | 12.2 °C | 24.6 °C | 127 mm |
| July | 14.8 °C | 26.8 °C | 103.89 mm |
| August | 13.9 °C | 26.2 °C | 112.01 mm |
| September | 9.9 °C | 22.4 °C | 99.06 mm |
| October | 4.2 °C | 15.5 °C | 96.52 mm |
| November | -0.8 °C | 8.4 °C | 90.42 mm |
| December | -5.6 °C | 2.5 °C | 82.3 mm |
| Annual | 2.7 °C | 13.8 °C | 1141.22 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 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |