Arnold, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 42.2 °F (low) to 62.1 °F (high). Annual precipitation averages 42.9 Inches. Arnold 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 | 21.3 °F | 37.4 °F | 3.36 in. |
| February | 22.4 °F | 40.3 °F | 2.63 in. |
| March | 29.1 °F | 49.2 °F | 3.23 in. |
| April | 39.4 °F | 62.8 °F | 3.55 in. |
| May | 50.2 °F | 72.8 °F | 3.96 in. |
| June | 59.4 °F | 80.7 °F | 4.49 in. |
| July | 63.3 °F | 84.5 °F | 4.44 in. |
| August | 62.1 °F | 83.2 °F | 3.7 in. |
| September | 55.1 °F | 76.5 °F | 3.87 in. |
| October | 43.7 °F | 64.0 °F | 3.17 in. |
| November | 33.9 °F | 52.0 °F | 3.15 in. |
| December | 26.6 °F | 41.6 °F | 3.31 in. |
| Annual | 42.2 °F | 62.1 °F | 42.86 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 6b : -5°F to 0°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |