Heron, Montana has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 1.5 °C (low) to 13.8 °C (high). Annual precipitation averages 814.8 Millimeters. Heron is located in USDA Plant Hardiness Zone 6b. 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 | -4.9 °C | 1.2 °C | 104.9 mm |
| February | -4.7 °C | 3.9 °C | 70.1 mm |
| March | -2.6 °C | 8.4 °C | 80.77 mm |
| April | 0.2 °C | 13.4 °C | 57.66 mm |
| May | 3.9 °C | 19.1 °C | 65.02 mm |
| June | 7.4 °C | 22.3 °C | 69.34 mm |
| July | 9.5 °C | 27.9 °C | 27.69 mm |
| August | 8.9 °C | 28.1 °C | 23.88 mm |
| September | 5.3 °C | 22.1 °C | 37.08 mm |
| October | 1.4 °C | 13.2 °C | 75.69 mm |
| November | -1.7 °C | 5.2 °C | 97.79 mm |
| December | -4.9 °C | 0.9 °C | 104.9 mm |
| Annual | 1.5 °C | 13.8 °C | 814.82 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 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |