Round Lake, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 4.2 °C (low) to 14.9 °C (high). Annual precipitation averages 1116.1 Millimeters. Round Lake is located in USDA Plant Hardiness Zone 6a. 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 °C | 0.2 °C | 78.23 mm |
| February | -8.3 °C | 1.8 °C | 63.25 mm |
| March | -3.6 °C | 6.8 °C | 81.53 mm |
| April | 2.7 °C | 14.8 °C | 90.93 mm |
| May | 9.2 °C | 21.4 °C | 91.44 mm |
| June | 14.2 °C | 26 °C | 118.11 mm |
| July | 16.8 °C | 28.7 °C | 117.6 mm |
| August | 16.1 °C | 27.4 °C | 105.16 mm |
| September | 11.8 °C | 23.4 °C | 96.01 mm |
| October | 5.5 °C | 16.3 °C | 105.66 mm |
| November | -0.1 °C | 9.3 °C | 79.76 mm |
| December | -5 °C | 3.1 °C | 88.39 mm |
| Annual | 4.2 °C | 14.9 °C | 1116.07 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°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 |