Hiram, Maine has a Subarctic With Cool Summers And Year Around Rainfall climate (Köppen classification: Dfc). Average annual temperatures range from -0.8 °C (low) to 12 °C (high). Annual precipitation averages 1352.8 Millimeters. 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 | -14.9 °C | -2.8 °C | 97.54 mm |
| February | -14.3 °C | -1.1 °C | 101.6 mm |
| March | -8.5 °C | 3.6 °C | 123.19 mm |
| April | -2.6 °C | 11.2 °C | 111.51 mm |
| May | 3.7 °C | 17.9 °C | 92.46 mm |
| June | 9.2 °C | 22.8 °C | 126.75 mm |
| July | 12.1 °C | 25.9 °C | 119.13 mm |
| August | 11.1 °C | 25.3 °C | 101.6 mm |
| September | 6.7 °C | 21.1 °C | 98.04 mm |
| October | 0.6 °C | 13.7 °C | 141.22 mm |
| November | -3.4 °C | 6.1 °C | 119.38 mm |
| December | -9.6 °C | 0.2 °C | 120.4 mm |
| Annual | -0.8 °C | 12 °C | 1352.82 mm |
| 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 : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfc - Subarctic With Cool Summers And Year Around Rainfall |