Orono, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.8 °C (low) to 12.4 °C (high). Annual precipitation averages 1067.1 Millimeters. Orono 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 | -13.7 °C | -2.3 °C | 86.11 mm |
| February | -12.8 °C | -0.7 °C | 64.77 mm |
| March | -6.7 °C | 4.1 °C | 83.82 mm |
| April | -0.4 °C | 11.1 °C | 86.36 mm |
| May | 5.4 °C | 18.1 °C | 82.04 mm |
| June | 10.4 °C | 23.2 °C | 94.23 mm |
| July | 14 °C | 26.3 °C | 80.26 mm |
| August | 12.8 °C | 25.7 °C | 79.25 mm |
| September | 8.6 °C | 21.2 °C | 88.14 mm |
| October | 2.6 °C | 13.8 °C | 113.28 mm |
| November | -2.3 °C | 7.3 °C | 97.28 mm |
| December | -8.7 °C | 1.2 °C | 111.51 mm |
| Annual | 0.8 °C | 12.4 °C | 1067.05 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 | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |