Norristown, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 44.8 °F (low) to 64.5 °F (high). Annual precipitation averages 48.1 Inches. Norristown 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 23.7 °F | 40.3 °F | 3.46 in. |
| February | 25.2 °F | 43.0 °F | 2.88 in. |
| March | 32.2 °F | 51.5 °F | 4.19 in. |
| April | 42.3 °F | 63.9 °F | 3.76 in. |
| May | 52.2 °F | 73.6 °F | 4.06 in. |
| June | 61.7 °F | 82.6 °F | 4.37 in. |
| July | 66.8 °F | 87.1 °F | 4.55 in. |
| August | 65.2 °F | 85.5 °F | 4.74 in. |
| September | 57.8 °F | 79.0 °F | 4.45 in. |
| October | 45.9 °F | 66.6 °F | 4.04 in. |
| November | 36.0 °F | 55.4 °F | 3.25 in. |
| December | 29.0 °F | 45.3 °F | 4.38 in. |
| Annual | 44.8 °F | 64.5 °F | 48.13 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| 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 7a : 0°F to 5°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |