Mackay, Idaho has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 27.7 °F (low) to 54.9 °F (high). Annual precipitation averages 9.8 Inches. 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 | 6.8 °F | 28.8 °F | 0.76 in. |
| February | 10.3 °F | 33.4 °F | 0.55 in. |
| March | 19.8 °F | 43.4 °F | 0.76 in. |
| April | 27.8 °F | 53.1 °F | 0.8 in. |
| May | 35.6 °F | 63.0 °F | 1.16 in. |
| June | 42.0 °F | 72.1 °F | 1.35 in. |
| July | 48.4 °F | 83.5 °F | 0.61 in. |
| August | 46.7 °F | 81.6 °F | 0.71 in. |
| September | 39.1 °F | 71.9 °F | 0.72 in. |
| October | 29.4 °F | 57.7 °F | 0.87 in. |
| November | 18.1 °F | 41.3 °F | 0.57 in. |
| December | 8.5 °F | 29.3 °F | 0.91 in. |
| Annual | 27.7 °F | 54.9 °F | 9.77 in. |
| 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 : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |