California Junction, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.1 °C (low) to 16.3 °C (high). Annual precipitation averages 821.2 Millimeters. California Junction is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.8 °C | -0.2 °C | 18.8 mm |
| February | -8.7 °C | 2.5 °C | 23.62 mm |
| March | -2.7 °C | 9.7 °C | 45.97 mm |
| April | 3.4 °C | 16.9 °C | 84.07 mm |
| May | 10.3 °C | 22.8 °C | 120.4 mm |
| June | 16.3 °C | 28.3 °C | 126.49 mm |
| July | 18.5 °C | 30.2 °C | 89.15 mm |
| August | 16.9 °C | 29.1 °C | 99.57 mm |
| September | 11.7 °C | 25.6 °C | 83.82 mm |
| October | 4.7 °C | 18.4 °C | 61.21 mm |
| November | -2.4 °C | 9.7 °C | 35.81 mm |
| December | -8.1 °C | 2.2 °C | 32.26 mm |
| Annual | 4.1 °C | 16.3 °C | 821.17 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 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 | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |