Graniteville, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 40.9 °F (low) to 62.7 °F (high). Annual precipitation averages 67.4 Inches. Graniteville is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 30.8 °F | 47.9 °F | 11.26 in. |
| February | 30.4 °F | 48.5 °F | 10.95 in. |
| March | 31.6 °F | 51.6 °F | 10.2 in. |
| April | 34.7 °F | 56.4 °F | 5.88 in. |
| May | 41.5 °F | 64.9 °F | 3.97 in. |
| June | 49.3 °F | 74.4 °F | 1.25 in. |
| July | 56.9 °F | 82.5 °F | 0.11 in. |
| August | 55.9 °F | 82.0 °F | 0.2 in. |
| September | 51.1 °F | 77.3 °F | 0.59 in. |
| October | 43.1 °F | 66.4 °F | 3.53 in. |
| November | 35.5 °F | 53.7 °F | 6.83 in. |
| December | 30.4 °F | 46.3 °F | 12.59 in. |
| Annual | 40.9 °F | 62.7 °F | 67.36 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 8b : 15°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 8a : 10°F to 15°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |