Effingham, New Hampshire has a Subarctic With Cool Summers And Year Around Rainfall climate (Köppen classification: Dfc). Average annual temperatures range from 33.7 °F (low) to 55.5 °F (high). Annual precipitation averages 49.8 Inches. Effingham is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 9.7 °F | 29.2 °F | 3.42 in. |
| February | 10.4 °F | 32.0 °F | 3.51 in. |
| March | 19.7 °F | 40.7 °F | 4.02 in. |
| April | 31.1 °F | 54.2 °F | 4.21 in. |
| May | 42.0 °F | 67.1 °F | 3.75 in. |
| June | 51.4 °F | 75.4 °F | 4.5 in. |
| July | 56.5 °F | 80.3 °F | 4.4 in. |
| August | 55.0 °F | 78.9 °F | 3.89 in. |
| September | 47.0 °F | 71.1 °F | 3.81 in. |
| October | 36.5 °F | 57.5 °F | 5.31 in. |
| November | 27.3 °F | 45.0 °F | 4.35 in. |
| December | 17.3 °F | 34.7 °F | 4.59 in. |
| Annual | 33.7 °F | 55.5 °F | 49.76 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfc - Subarctic With Cool Summers And Year Around Rainfall |