Porter, Maine has a Subarctic With Cool Summers And Year Around Rainfall climate (Köppen classification: Dfc). Average annual temperatures range from 0.4 °C (low) to 13 °C (high). Annual precipitation averages 1305 Millimeters. Porter 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 | -13.5 °C | -1.6 °C | 91.19 mm |
| February | -12.9 °C | 0.1 °C | 92.96 mm |
| March | -7.4 °C | 4.8 °C | 109.98 mm |
| April | -1 °C | 12.2 °C | 112.01 mm |
| May | 5.1 °C | 19.2 °C | 95.76 mm |
| June | 10.5 °C | 23.7 °C | 120.4 mm |
| July | 13.3 °C | 26.7 °C | 113.28 mm |
| August | 12.3 °C | 25.9 °C | 98.3 mm |
| September | 7.9 °C | 21.7 °C | 98.55 mm |
| October | 1.9 °C | 14.2 °C | 139.95 mm |
| November | -3.1 °C | 7.2 °C | 114.3 mm |
| December | -8.9 °C | 1.3 °C | 118.36 mm |
| Annual | 0.4 °C | 13 °C | 1305.04 mm |
| 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 : -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 |