Johnstonville, California has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 35.2 °F (low) to 64.8 °F (high). Annual precipitation averages 16.6 Inches. Johnstonville is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 22.9 °F | 43.4 °F | 3.41 in. |
| February | 25.2 °F | 47.6 °F | 2.52 in. |
| March | 29.8 °F | 54.5 °F | 2.03 in. |
| April | 32.7 °F | 60.6 °F | 0.84 in. |
| May | 39.2 °F | 70.2 °F | 0.96 in. |
| June | 45.2 °F | 80.3 °F | 0.59 in. |
| July | 51.3 °F | 89.5 °F | 0.21 in. |
| August | 49.6 °F | 88.1 °F | 0.16 in. |
| September | 43.1 °F | 81.0 °F | 0.26 in. |
| October | 34.8 °F | 67.2 °F | 1.09 in. |
| November | 27.1 °F | 52.5 °F | 1.39 in. |
| December | 22.0 °F | 42.6 °F | 3.12 in. |
| Annual | 35.2 °F | 64.8 °F | 16.58 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 7a : 0°F to 5°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |