Downey, Idaho has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -0.6 °C (low) to 15 °C (high). Annual precipitation averages 333.8 Millimeters. Downey is located in USDA Plant Hardiness Zone 5b. 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 | -10.4 °C | 0.3 °C | 27.43 mm |
| February | -8.7 °C | 2.8 °C | 24.13 mm |
| March | -4.3 °C | 8.6 °C | 37.59 mm |
| April | -1.1 °C | 13.6 °C | 34.54 mm |
| May | 2.9 °C | 19.1 °C | 41.15 mm |
| June | 6.2 °C | 24.9 °C | 21.08 mm |
| July | 9.9 °C | 31.3 °C | 19.3 mm |
| August | 9.1 °C | 30.4 °C | 21.59 mm |
| September | 4.3 °C | 24.4 °C | 34.29 mm |
| October | -0.7 °C | 16.1 °C | 29.97 mm |
| November | -5.5 °C | 7.4 °C | 22.61 mm |
| December | -9.4 °C | 1.1 °C | 20.07 mm |
| Annual | -0.6 °C | 15 °C | 333.75 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 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |