Mackay, Idaho has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -2.4 °C (low) to 12.7 °C (high). Annual precipitation averages 248.1 Millimeters. Mackay is located in USDA Plant Hardiness Zone 5b. 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 | -14 °C | -1.8 °C | 19.3 mm |
| February | -12.1 °C | 0.8 °C | 13.97 mm |
| March | -6.8 °C | 6.3 °C | 19.3 mm |
| April | -2.3 °C | 11.7 °C | 20.32 mm |
| May | 2 °C | 17.2 °C | 29.46 mm |
| June | 5.6 °C | 22.3 °C | 34.29 mm |
| July | 9.1 °C | 28.6 °C | 15.49 mm |
| August | 8.2 °C | 27.6 °C | 18.03 mm |
| September | 3.9 °C | 22.2 °C | 18.29 mm |
| October | -1.4 °C | 14.3 °C | 22.1 mm |
| November | -7.7 °C | 5.2 °C | 14.48 mm |
| December | -13.1 °C | -1.5 °C | 23.11 mm |
| Annual | -2.4 °C | 12.7 °C | 248.14 mm |
| Average First Frost Date | Sep.1 - Sep. 10 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |