Hartford, Connecticut has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.3 °C (low) to 16 °C (high). Annual precipitation averages 1287.5 Millimeters. Hartford is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7 °C | 2.3 °C | 95 mm |
| February | -6.3 °C | 3.8 °C | 83.31 mm |
| March | -2 °C | 8.3 °C | 110.49 mm |
| April | 3.8 °C | 15.3 °C | 106.93 mm |
| May | 9.6 °C | 21.3 °C | 93.73 mm |
| June | 14.8 °C | 26 °C | 120.65 mm |
| July | 17.8 °C | 29 °C | 106.93 mm |
| August | 16.9 °C | 28.2 °C | 108.71 mm |
| September | 12.7 °C | 24.2 °C | 119.13 mm |
| October | 6.3 °C | 17.4 °C | 130.81 mm |
| November | 0.8 °C | 10.9 °C | 97.28 mm |
| December | -3.6 °C | 5.3 °C | 114.55 mm |
| Annual | 5.3 °C | 16 °C | 1287.52 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |