Fairfield, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 42.7 °F (low) to 63.1 °F (high). Annual precipitation averages 45.7 Inches. Fairfield is located in USDA Plant Hardiness Zone 7a. 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 | 22.0 °F | 38.8 °F | 3.41 in. |
| February | 23.3 °F | 42.2 °F | 2.69 in. |
| March | 30.3 °F | 50.6 °F | 3.9 in. |
| April | 40.5 °F | 63.1 °F | 3.87 in. |
| May | 50.5 °F | 72.4 °F | 4.36 in. |
| June | 59.6 °F | 80.9 °F | 4.1 in. |
| July | 64.1 °F | 85.7 °F | 3.9 in. |
| August | 62.3 °F | 83.8 °F | 3.76 in. |
| September | 55.2 °F | 77.2 °F | 4.86 in. |
| October | 43.6 °F | 65.5 °F | 3.91 in. |
| November | 33.8 °F | 53.9 °F | 3.28 in. |
| December | 26.7 °F | 43.1 °F | 3.64 in. |
| Annual | 42.7 °F | 63.1 °F | 45.68 in. |
| 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 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |