Happys Inn, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -2.2 °C (low) to 12.9 °C (high). Annual precipitation averages 520 Millimeters. Happys Inn is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around Jun. 11 - Jun. 20 through the first frost around Aug. 1 - Aug. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.6 °C | 0.4 °C | 52.07 mm |
| February | -9.4 °C | 2.8 °C | 39.37 mm |
| March | -6 °C | 7.4 °C | 48.77 mm |
| April | -2.5 °C | 12.3 °C | 36.32 mm |
| May | 1.3 °C | 17.8 °C | 49.53 mm |
| June | 4.3 °C | 21.3 °C | 52.83 mm |
| July | 6.2 °C | 27.3 °C | 21.34 mm |
| August | 5.2 °C | 27.3 °C | 19.56 mm |
| September | 1.5 °C | 21.3 °C | 28.7 mm |
| October | -2.3 °C | 12.6 °C | 49.28 mm |
| November | -5.8 °C | 4.4 °C | 63.25 mm |
| December | -9.1 °C | -0.4 °C | 58.93 mm |
| Annual | -2.2 °C | 12.9 °C | 519.95 mm |
| Average First Frost Date | Aug. 1 - Aug. 10 |
| Average Last Frost Date | Jun. 11 - Jun. 20 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |