Stillwater, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 36.5 °F (low) to 55.3 °F (high). Annual precipitation averages 34.5 Inches. Stillwater is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 6.9 °F | 24.0 °F | 0.93 in. |
| February | 10.2 °F | 29.0 °F | 0.87 in. |
| March | 22.2 °F | 41.3 °F | 1.62 in. |
| April | 35.5 °F | 56.2 °F | 3.18 in. |
| May | 48.1 °F | 68.5 °F | 4.21 in. |
| June | 58.5 °F | 78.3 °F | 5.05 in. |
| July | 63.1 °F | 82.7 °F | 4.37 in. |
| August | 60.5 °F | 80.5 °F | 4.7 in. |
| September | 52.2 °F | 72.8 °F | 3.53 in. |
| October | 39.3 °F | 58.7 °F | 3.06 in. |
| November | 26.7 °F | 42.8 °F | 1.73 in. |
| December | 14.3 °F | 29.1 °F | 1.28 in. |
| Annual | 36.5 °F | 55.3 °F | 34.53 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |