Happys Inn, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 28.1 °F (low) to 55.2 °F (high). Annual precipitation averages 20.5 Inches. 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 | 14.8 °F | 32.7 °F | 2.05 in. |
| February | 15.1 °F | 37.1 °F | 1.55 in. |
| March | 21.2 °F | 45.4 °F | 1.92 in. |
| April | 27.5 °F | 54.1 °F | 1.43 in. |
| May | 34.3 °F | 64.0 °F | 1.95 in. |
| June | 39.8 °F | 70.4 °F | 2.08 in. |
| July | 43.1 °F | 81.1 °F | 0.84 in. |
| August | 41.4 °F | 81.1 °F | 0.77 in. |
| September | 34.7 °F | 70.4 °F | 1.13 in. |
| October | 27.8 °F | 54.7 °F | 1.94 in. |
| November | 21.6 °F | 39.9 °F | 2.49 in. |
| December | 15.6 °F | 31.2 °F | 2.32 in. |
| Annual | 28.1 °F | 55.2 °F | 20.47 in. |
| 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 : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |