Johnsville, California has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 0.8 °C (low) to 16.5 °C (high). Annual precipitation averages 1480.1 Millimeters. Johnsville is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Jun. 11 - Jun. 20 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.3 °C | 6.7 °C | 268.22 mm |
| February | -5.1 °C | 7.9 °C | 235.46 mm |
| March | -3.2 °C | 10.4 °C | 225.81 mm |
| April | -1.3 °C | 13.8 °C | 129.03 mm |
| May | 2.4 °C | 18.6 °C | 80.77 mm |
| June | 5.8 °C | 23.7 °C | 25.91 mm |
| July | 9.1 °C | 28.5 °C | 4.32 mm |
| August | 8.4 °C | 28.1 °C | 4.83 mm |
| September | 5.3 °C | 25.7 °C | 17.53 mm |
| October | 1.2 °C | 18.5 °C | 74.17 mm |
| November | -2.9 °C | 10.7 °C | 138.18 mm |
| December | -5.3 °C | 5.9 °C | 275.84 mm |
| Annual | 0.8 °C | 16.5 °C | 1480.07 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | Jun. 11 - Jun. 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 7b : -15°C to -12.2°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |