Arimo, Idaho has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -0.3 °C (low) to 15.4 °C (high). Annual precipitation averages 373.4 Millimeters. Arimo is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.9 °C | 0.4 °C | 40.89 mm |
| February | -8.2 °C | 3.3 °C | 32 mm |
| March | -3.7 °C | 9.1 °C | 35.31 mm |
| April | -0.8 °C | 14.4 °C | 32 mm |
| May | 3.4 °C | 19.7 °C | 44.2 mm |
| June | 6.5 °C | 25.2 °C | 25.65 mm |
| July | 10.4 °C | 31.2 °C | 16.51 mm |
| August | 9.7 °C | 30.6 °C | 22.35 mm |
| September | 4.5 °C | 24.7 °C | 32.51 mm |
| October | -0.6 °C | 16.8 °C | 30.48 mm |
| November | -5.5 °C | 7.6 °C | 23.11 mm |
| December | -9.2 °C | 1.2 °C | 38.35 mm |
| Annual | -0.3 °C | 15.4 °C | 373.36 mm |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 11 - May 20 |
| 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 |