Grayson, California has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 9.1 °C (low) to 23.2 °C (high). Annual precipitation averages 293.6 Millimeters. Grayson 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 | 3.6 °C | 12.9 °C | 61.47 mm |
| February | 4.9 °C | 16.1 °C | 52.83 mm |
| March | 6.3 °C | 19.2 °C | 42.93 mm |
| April | 8.1 °C | 21.8 °C | 23.11 mm |
| May | 10.8 °C | 26.1 °C | 14.73 mm |
| June | 13.4 °C | 30.2 °C | 2.29 mm |
| July | 15 °C | 32.8 °C | 0 mm |
| August | 14.7 °C | 32.1 °C | 0.51 mm |
| September | 13.1 °C | 30.1 °C | 2.03 mm |
| October | 9.8 °C | 25.1 °C | 14.99 mm |
| November | 5.7 °C | 18.4 °C | 26.16 mm |
| December | 3.4 °C | 13.2 °C | 52.58 mm |
| Annual | 9.1 °C | 23.2 °C | 293.63 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 | BSk - Cold Semi-Arid Climate |