Gilroy, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 46.5 °F (low) to 73 °F (high). Annual precipitation averages 19.9 Inches. Gilroy is located in USDA Plant Hardiness Zone 9b. The growing season typically runs from the last frost around Feb. 1 - Feb. 10 through the first frost around Dec. 1 - Dec. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 39.5 °F | 60.5 °F | 4.14 in. |
| February | 41.2 °F | 62.3 °F | 4.47 in. |
| March | 43.0 °F | 65.5 °F | 2.81 in. |
| April | 44.7 °F | 70.4 °F | 1.28 in. |
| May | 48.2 °F | 75.6 °F | 0.51 in. |
| June | 51.2 °F | 81.5 °F | 0.1 in. |
| July | 53.9 °F | 84.3 °F | 0.0 in. |
| August | 54.2 °F | 85.2 °F | 0.03 in. |
| September | 52.6 °F | 84.2 °F | 0.05 in. |
| October | 48.3 °F | 78.6 °F | 0.8 in. |
| November | 42.7 °F | 67.2 °F | 1.59 in. |
| December | 38.5 °F | 60.2 °F | 4.09 in. |
| Annual | 46.5 °F | 73 °F | 19.87 in. |
| Average First Frost Date | Dec. 1 - Dec. 10 |
| Average Last Frost Date | Feb. 1 - Feb. 10 |
| Average Days With Frost | 10-20 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 | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |