Roxbury, Connecticut has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.2 °C (low) to 15.1 °C (high). Annual precipitation averages 1225.8 Millimeters. Roxbury is located in USDA Plant Hardiness Zone 6b. 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 | -8 °C | 1.7 °C | 82.55 mm |
| February | -7.1 °C | 3.2 °C | 70.61 mm |
| March | -3.2 °C | 7.7 °C | 95.5 mm |
| April | 2.7 °C | 14.7 °C | 94.49 mm |
| May | 8.4 °C | 20.5 °C | 101.35 mm |
| June | 13.4 °C | 24.9 °C | 109.47 mm |
| July | 16.5 °C | 27.6 °C | 135.64 mm |
| August | 15.8 °C | 26.6 °C | 113.28 mm |
| September | 11.8 °C | 22.7 °C | 108.2 mm |
| October | 5.2 °C | 16.4 °C | 122.68 mm |
| November | 0 °C | 10.3 °C | 91.69 mm |
| December | -4.7 °C | 4.3 °C | 100.33 mm |
| Annual | 4.2 °C | 15.1 °C | 1225.79 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 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |