Spencer, Idaho has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -2.2 °C (low) to 11.9 °C (high). Annual precipitation averages 479.8 Millimeters. Spencer is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Jun. 1 - Jun. 10 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -12.4 °C | -2.7 °C | 39.12 mm |
| February | -11.2 °C | -0.6 °C | 34.04 mm |
| March | -7 °C | 4.9 °C | 33.53 mm |
| April | -2.7 °C | 11.2 °C | 42.42 mm |
| May | 1.8 °C | 16.8 °C | 77.22 mm |
| June | 5.4 °C | 21.8 °C | 51.31 mm |
| July | 9 °C | 27.9 °C | 27.69 mm |
| August | 8.2 °C | 27.5 °C | 23.11 mm |
| September | 4 °C | 21.6 °C | 27.18 mm |
| October | -1.7 °C | 12.6 °C | 43.69 mm |
| November | -7.5 °C | 3.8 °C | 31.5 mm |
| December | -12.2 °C | -2.4 °C | 49.02 mm |
| Annual | -2.2 °C | 11.9 °C | 479.83 mm |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | Jun. 1 - Jun. 10 |
| 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 |