Altona, Colorado has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 2.8 °C (low) to 17.9 °C (high). Annual precipitation averages 491 Millimeters. Altona is located in USDA Plant Hardiness Zone 6a. 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 | -6.5 °C | 7.4 °C | 17.27 mm |
| February | -6.1 °C | 7.9 °C | 21.34 mm |
| March | -2.2 °C | 12.7 °C | 42.42 mm |
| April | 1 °C | 15.8 °C | 64.77 mm |
| May | 6 °C | 20.6 °C | 80.26 mm |
| June | 11.1 °C | 27.3 °C | 52.32 mm |
| July | 14.5 °C | 30.8 °C | 47.24 mm |
| August | 13.4 °C | 29.6 °C | 39.12 mm |
| September | 9.1 °C | 25.3 °C | 50.04 mm |
| October | 2.8 °C | 18.1 °C | 35.81 mm |
| November | -2.5 °C | 11.7 °C | 23.37 mm |
| December | -6.6 °C | 7.1 °C | 17.02 mm |
| Annual | 2.8 °C | 17.9 °C | 490.98 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 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |