Bristol, Connecticut has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.5 °C (low) to 16 °C (high). Annual precipitation averages 1331.5 Millimeters. Bristol 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 | -7.7 °C | 2.3 °C | 93.73 mm |
| February | -7 °C | 3.9 °C | 85.6 mm |
| March | -2.9 °C | 8.3 °C | 117.86 mm |
| April | 2.9 °C | 15.4 °C | 104.14 mm |
| May | 8.6 °C | 21.5 °C | 102.87 mm |
| June | 13.8 °C | 26.2 °C | 116.08 mm |
| July | 16.8 °C | 29.1 °C | 114.3 mm |
| August | 15.8 °C | 28.1 °C | 112.52 mm |
| September | 11.8 °C | 24.1 °C | 122.94 mm |
| October | 5.4 °C | 17.3 °C | 139.45 mm |
| November | 0.1 °C | 10.9 °C | 103.12 mm |
| December | -4.2 °C | 5.2 °C | 118.87 mm |
| Annual | 4.5 °C | 16 °C | 1331.48 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 |