Grimes, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 9.3 °C (low) to 23.9 °C (high). Annual precipitation averages 469.1 Millimeters. Grimes 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 | 3.8 °C | 13.1 °C | 89.15 mm |
| February | 5.1 °C | 16.1 °C | 99.06 mm |
| March | 6.5 °C | 19.1 °C | 56.39 mm |
| April | 7.9 °C | 22.5 °C | 33.53 mm |
| May | 11.5 °C | 27.1 °C | 19.56 mm |
| June | 14.4 °C | 31.4 °C | 6.6 mm |
| July | 15.7 °C | 34.4 °C | 0.25 mm |
| August | 14.8 °C | 33.9 °C | 3.3 mm |
| September | 13.1 °C | 31.8 °C | 4.57 mm |
| October | 9.5 °C | 26.2 °C | 22.35 mm |
| November | 5.6 °C | 18.2 °C | 49.02 mm |
| December | 3.4 °C | 13.1 °C | 85.34 mm |
| Annual | 9.3 °C | 23.9 °C | 469.12 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 | Abnormally Dry |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |