Pioneer Junction, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.6 °C (low) to 14.6 °C (high). Annual precipitation averages 459.5 Millimeters. Pioneer Junction is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -6.6 °C | 0.6 °C | 47.5 mm |
| February | -6.3 °C | 4.1 °C | 32 mm |
| March | -3.6 °C | 9.3 °C | 45.21 mm |
| April | -0.7 °C | 14.7 °C | 27.43 mm |
| May | 3.4 °C | 20.3 °C | 38.86 mm |
| June | 7.1 °C | 24 °C | 45.97 mm |
| July | 9.1 °C | 29.9 °C | 22.1 mm |
| August | 8.4 °C | 30 °C | 17.53 mm |
| September | 4.6 °C | 23.4 °C | 25.15 mm |
| October | 0.6 °C | 13.6 °C | 42.67 mm |
| November | -2.8 °C | 4.6 °C | 58.42 mm |
| December | -6.1 °C | 0.1 °C | 56.64 mm |
| Annual | 0.6 °C | 14.6 °C | 459.48 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |