Starr School, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -1.4 °C (low) to 10.6 °C (high). Annual precipitation averages 557.8 Millimeters. Starr School is located in USDA Plant Hardiness Zone 4a. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep.1 - Sep. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.1 °C | -0.2 °C | 36.83 mm |
| February | -10 °C | 0.6 °C | 38.61 mm |
| March | -6.8 °C | 4.1 °C | 41.66 mm |
| April | -2.4 °C | 8.9 °C | 47.75 mm |
| May | 1.8 °C | 14.2 °C | 66.04 mm |
| June | 5.6 °C | 18.4 °C | 90.93 mm |
| July | 8.3 °C | 24.2 °C | 32.51 mm |
| August | 7.6 °C | 24.1 °C | 28.7 mm |
| September | 3.9 °C | 18.3 °C | 39.12 mm |
| October | -0.6 °C | 10.6 °C | 46.48 mm |
| November | -4.8 °C | 3.9 °C | 50.04 mm |
| December | -9.1 °C | -0.2 °C | 39.12 mm |
| Annual | -1.4 °C | 10.6 °C | 557.79 mm |
| Average First Frost Date | Sep.1 - Sep. 10 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4a : -34.4°C to -31.7°C |
| Plant Hardiness Zone - 2012 | Zone 4a : -34.4°C to -31.7°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |