Casselman, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 37.2 °F (low) to 59.2 °F (high). Annual precipitation averages 46.4 Inches. Casselman is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 17.0 °F | 35.0 °F | 3.58 in. |
| February | 18.3 °F | 37.9 °F | 3.22 in. |
| March | 25.0 °F | 46.5 °F | 3.98 in. |
| April | 35.1 °F | 60.1 °F | 4.02 in. |
| May | 45.2 °F | 69.5 °F | 4.74 in. |
| June | 53.6 °F | 77.1 °F | 4.71 in. |
| July | 57.6 °F | 80.8 °F | 4.31 in. |
| August | 56.1 °F | 79.6 °F | 3.95 in. |
| September | 48.9 °F | 73.4 °F | 3.81 in. |
| October | 38.3 °F | 61.8 °F | 3.3 in. |
| November | 28.9 °F | 49.5 °F | 3.16 in. |
| December | 22.3 °F | 39.3 °F | 3.66 in. |
| Annual | 37.2 °F | 59.2 °F | 46.44 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |