Alton, Utah has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -0.2 °C (low) to 16.1 °C (high). Annual precipitation averages 440.2 Millimeters. Alton is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Jun. 1 - Jun. 10 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.9 °C | 5 °C | 49.02 mm |
| February | -7.9 °C | 6.3 °C | 49.78 mm |
| March | -4.8 °C | 10.2 °C | 40.89 mm |
| April | -2.1 °C | 14.2 °C | 22.1 mm |
| May | 1.9 °C | 19.3 °C | 21.59 mm |
| June | 6.3 °C | 25.7 °C | 10.92 mm |
| July | 10.5 °C | 28.8 °C | 30.23 mm |
| August | 9.9 °C | 27.6 °C | 46.99 mm |
| September | 5.9 °C | 23.6 °C | 43.94 mm |
| October | 0.4 °C | 17.1 °C | 46.23 mm |
| November | -4.9 °C | 10.3 °C | 31.5 mm |
| December | -9.1 °C | 4.9 °C | 46.99 mm |
| Annual | -0.2 °C | 16.1 °C | 440.18 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | Jun. 1 - Jun. 10 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |