Hiram, Maine has a Subarctic With Cool Summers And Year Around Rainfall climate (Köppen classification: Dfc). Average annual temperatures range from 30.5 °F (low) to 53.6 °F (high). Annual precipitation averages 53.3 Inches. Hiram is located in USDA Plant Hardiness Zone 5a. 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 | 5.2 °F | 26.9 °F | 3.84 in. |
| February | 6.3 °F | 30.1 °F | 4.0 in. |
| March | 16.7 °F | 38.5 °F | 4.85 in. |
| April | 27.4 °F | 52.1 °F | 4.39 in. |
| May | 38.6 °F | 64.3 °F | 3.64 in. |
| June | 48.5 °F | 73.0 °F | 4.99 in. |
| July | 53.7 °F | 78.6 °F | 4.69 in. |
| August | 52.0 °F | 77.5 °F | 4.0 in. |
| September | 44.1 °F | 69.9 °F | 3.86 in. |
| October | 33.0 °F | 56.6 °F | 5.56 in. |
| November | 25.8 °F | 43.0 °F | 4.7 in. |
| December | 14.8 °F | 32.3 °F | 4.74 in. |
| Annual | 30.5 °F | 53.6 °F | 53.26 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| 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 | Abnormally Dry |
| Köppen Climate Classification | Dfc - Subarctic With Cool Summers And Year Around Rainfall |