Corvallis, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 32.5 °F (low) to 59.1 °F (high). Annual precipitation averages 11.8 Inches. Corvallis is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 18.6 °F | 35.7 °F | 0.8 in. |
| February | 20.5 °F | 40.6 °F | 0.73 in. |
| March | 25.8 °F | 50.0 °F | 0.77 in. |
| April | 31.2 °F | 58.2 °F | 0.99 in. |
| May | 38.1 °F | 67.5 °F | 1.56 in. |
| June | 44.5 °F | 74.8 °F | 1.52 in. |
| July | 49.2 °F | 86.0 °F | 0.82 in. |
| August | 47.6 °F | 84.8 °F | 0.85 in. |
| September | 40.4 °F | 74.3 °F | 0.89 in. |
| October | 31.7 °F | 59.2 °F | 0.81 in. |
| November | 23.9 °F | 43.3 °F | 0.99 in. |
| December | 18.3 °F | 34.3 °F | 1.04 in. |
| Annual | 32.5 °F | 59.1 °F | 11.77 in. |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |