Brookhaven, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 8.8 °C (low) to 17.7 °C (high). Annual precipitation averages 1162.3 Millimeters. Brookhaven is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -2.9 °C | 4.7 °C | 89.66 mm |
| February | -2.2 °C | 6.1 °C | 72.64 mm |
| March | 1.5 °C | 10.5 °C | 108.46 mm |
| April | 7.3 °C | 17.2 °C | 90.17 mm |
| May | 12.7 °C | 22.4 °C | 93.22 mm |
| June | 17.9 °C | 27.6 °C | 112.52 mm |
| July | 21 °C | 30 °C | 117.35 mm |
| August | 20.2 °C | 29.1 °C | 109.98 mm |
| September | 16.4 °C | 25.6 °C | 104.14 mm |
| October | 9.8 °C | 18.9 °C | 92.96 mm |
| November | 4.2 °C | 12.9 °C | 72.64 mm |
| December | 0.1 °C | 7.4 °C | 98.55 mm |
| Annual | 8.8 °C | 17.7 °C | 1162.29 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7b : -15°C to -12.2°C |
| Plant Hardiness Zone - 2012 | Zone 7b : -15°C to -12.2°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |