Gridley, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 9.6 °C (low) to 23.7 °C (high). Annual precipitation averages 646.7 Millimeters. Gridley 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. 11 - Dec. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 3.9 °C | 13.1 °C | 120.65 mm |
| February | 5.3 °C | 16 °C | 106.17 mm |
| March | 6.6 °C | 19 °C | 94.74 mm |
| April | 8.1 °C | 22.3 °C | 44.2 mm |
| May | 11.8 °C | 27.1 °C | 35.05 mm |
| June | 14.9 °C | 31.3 °C | 8.89 mm |
| July | 16.6 °C | 34.2 °C | 0.25 mm |
| August | 15.6 °C | 33.6 °C | 1.02 mm |
| September | 13.5 °C | 31.3 °C | 9.4 mm |
| October | 9.8 °C | 25.8 °C | 29.21 mm |
| November | 5.8 °C | 18.1 °C | 65.28 mm |
| December | 3.6 °C | 13.1 °C | 131.83 mm |
| Annual | 9.6 °C | 23.7 °C | 646.69 mm |
| Average First Frost Date | Dec. 11 - Dec. 20 |
| 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 | Abnormally Dry |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |