Smithfield, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 42 °F (low) to 62.8 °F (high). Annual precipitation averages 44.7 Inches. Smithfield 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. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 21.8 °F | 38.6 °F | 3.34 in. |
| February | 23.4 °F | 41.8 °F | 2.89 in. |
| March | 29.8 °F | 50.9 °F | 3.65 in. |
| April | 39.7 °F | 64.0 °F | 3.85 in. |
| May | 49.9 °F | 73.3 °F | 4.43 in. |
| June | 58.5 °F | 80.6 °F | 4.5 in. |
| July | 62.7 °F | 84.0 °F | 4.72 in. |
| August | 61.4 °F | 83.2 °F | 3.87 in. |
| September | 54.3 °F | 77.0 °F | 3.63 in. |
| October | 42.9 °F | 64.7 °F | 3.19 in. |
| November | 33.2 °F | 52.9 °F | 3.26 in. |
| December | 26.8 °F | 42.6 °F | 3.4 in. |
| Annual | 42 °F | 62.8 °F | 44.73 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| 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 6b : -5°F to 0°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |