California Junction, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 39.4 °F (low) to 61.3 °F (high). Annual precipitation averages 32.3 Inches. 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 | 12.5 °F | 31.6 °F | 0.74 in. |
| February | 16.3 °F | 36.5 °F | 0.93 in. |
| March | 27.1 °F | 49.5 °F | 1.81 in. |
| April | 38.1 °F | 62.5 °F | 3.31 in. |
| May | 50.6 °F | 73.0 °F | 4.74 in. |
| June | 61.4 °F | 83.0 °F | 4.98 in. |
| July | 65.3 °F | 86.4 °F | 3.51 in. |
| August | 62.4 °F | 84.4 °F | 3.92 in. |
| September | 53.1 °F | 78.1 °F | 3.3 in. |
| October | 40.4 °F | 65.1 °F | 2.41 in. |
| November | 27.7 °F | 49.4 °F | 1.41 in. |
| December | 17.5 °F | 35.9 °F | 1.27 in. |
| Annual | 39.4 °F | 61.3 °F | 32.33 in. |
| 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 : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |