Three Rivers, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 50.6 °F (low) to 78.1 °F (high). Annual precipitation averages 20.5 Inches. Three Rivers is located in USDA Plant Hardiness Zone 9b. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Nov. 21 - Nov. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 38.2 °F | 58.7 °F | 4.26 in. |
| February | 40.5 °F | 63.0 °F | 3.57 in. |
| March | 43.8 °F | 68.7 °F | 3.43 in. |
| April | 46.9 °F | 74.6 °F | 1.76 in. |
| May | 53.4 °F | 83.3 °F | 0.81 in. |
| June | 60.0 °F | 91.9 °F | 0.23 in. |
| July | 66.6 °F | 98.5 °F | 0.1 in. |
| August | 65.3 °F | 98.2 °F | 0.02 in. |
| September | 60.3 °F | 93.0 °F | 0.2 in. |
| October | 51.5 °F | 81.6 °F | 0.84 in. |
| November | 42.9 °F | 67.5 °F | 1.74 in. |
| December | 37.5 °F | 58.6 °F | 3.5 in. |
| Annual | 50.6 °F | 78.1 °F | 20.46 in. |
| Average First Frost Date | Nov. 21 - Nov. 30 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 20-30 Days |
| Plant Hardiness Zone | Zone 9b : 25°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 9b : 25°F to 20°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |