Washington, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 40.3 °F (low) to 61.6 °F (high). Annual precipitation averages 41.7 Inches. Washington 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 | 19.8 °F | 37.0 °F | 3.21 in. |
| February | 21.2 °F | 40.0 °F | 2.39 in. |
| March | 28.3 °F | 49.4 °F | 3.39 in. |
| April | 38.0 °F | 62.3 °F | 3.29 in. |
| May | 48.0 °F | 71.8 °F | 4.34 in. |
| June | 56.9 °F | 79.4 °F | 4.59 in. |
| July | 60.9 °F | 83.5 °F | 4.15 in. |
| August | 59.3 °F | 82.3 °F | 3.49 in. |
| September | 52.5 °F | 76.1 °F | 3.58 in. |
| October | 41.1 °F | 64.0 °F | 3.16 in. |
| November | 32.1 °F | 52.1 °F | 2.98 in. |
| December | 25.0 °F | 41.6 °F | 3.15 in. |
| Annual | 40.3 °F | 61.6 °F | 41.72 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |