Gilroy, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 8.1 °C (low) to 22.8 °C (high). Annual precipitation averages 504.7 Millimeters. 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 | 4.2 °C | 15.8 °C | 105.16 mm |
| February | 5.1 °C | 16.8 °C | 113.54 mm |
| March | 6.1 °C | 18.6 °C | 71.37 mm |
| April | 7.1 °C | 21.3 °C | 32.51 mm |
| May | 9 °C | 24.2 °C | 12.95 mm |
| June | 10.7 °C | 27.5 °C | 2.54 mm |
| July | 12.2 °C | 29.1 °C | 0 mm |
| August | 12.3 °C | 29.6 °C | 0.76 mm |
| September | 11.4 °C | 29 °C | 1.27 mm |
| October | 9.1 °C | 25.9 °C | 20.32 mm |
| November | 5.9 °C | 19.6 °C | 40.39 mm |
| December | 3.6 °C | 15.7 °C | 103.89 mm |
| Annual | 8.1 °C | 22.8 °C | 504.7 mm |
| 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 : -3.9°C to -1.1°C |
| Plant Hardiness Zone - 2012 | Zone 9b : -3.9°C to -1.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |