Bristol, Pennsylvania has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 7.8 °C (low) to 18.2 °C (high). Annual precipitation averages 1194.1 Millimeters. Bristol is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -3.8 °C | 5.2 °C | 89.92 mm |
| February | -3.2 °C | 6.7 °C | 68.33 mm |
| March | 0.8 °C | 11 °C | 110.74 mm |
| April | 6.3 °C | 17.7 °C | 88.39 mm |
| May | 11.7 °C | 23 °C | 99.82 mm |
| June | 17 °C | 28.1 °C | 107.95 mm |
| July | 20 °C | 30.6 °C | 121.92 mm |
| August | 19 °C | 29.7 °C | 123.19 mm |
| September | 15.1 °C | 26.1 °C | 98.04 mm |
| October | 8.6 °C | 19.5 °C | 97.54 mm |
| November | 3 °C | 13.4 °C | 79.76 mm |
| December | -1 °C | 7.8 °C | 108.46 mm |
| Annual | 7.8 °C | 18.2 °C | 1194.06 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7b : -15°C to -12.2°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |