Janesville, California has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 34.7 °F (low) to 64.7 °F (high). Annual precipitation averages 17 Inches. Janesville 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 | 22.6 °F | 43.7 °F | 3.3 in. |
| February | 24.7 °F | 47.9 °F | 2.63 in. |
| March | 29.0 °F | 54.3 °F | 2.09 in. |
| April | 32.3 °F | 60.4 °F | 0.91 in. |
| May | 38.7 °F | 69.7 °F | 1.01 in. |
| June | 44.7 °F | 79.9 °F | 0.65 in. |
| July | 50.7 °F | 89.1 °F | 0.26 in. |
| August | 48.7 °F | 87.9 °F | 0.18 in. |
| September | 42.3 °F | 80.8 °F | 0.26 in. |
| October | 34.1 °F | 67.1 °F | 1.06 in. |
| November | 26.9 °F | 52.4 °F | 1.42 in. |
| December | 22.0 °F | 42.7 °F | 3.22 in. |
| Annual | 34.7 °F | 64.7 °F | 16.99 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 |