Diablo Grande, California has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 10.4 °C (low) to 22.6 °C (high). Annual precipitation averages 372.1 Millimeters. Diablo Grande is located in USDA Plant Hardiness Zone 9b. The growing season typically runs from the last frost around Mar. 1 - Mar. 10 through the first frost around Nov. 21 - Nov. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 4.7 °C | 12.7 °C | 84.84 mm |
| February | 5.9 °C | 14.5 °C | 76.71 mm |
| March | 7.1 °C | 17.3 °C | 53.59 mm |
| April | 8.4 °C | 20.4 °C | 21.08 mm |
| May | 11.3 °C | 24.9 °C | 14.73 mm |
| June | 14.3 °C | 29.3 °C | 2.29 mm |
| July | 17 °C | 33.2 °C | 0 mm |
| August | 16.7 °C | 32.9 °C | 0.51 mm |
| September | 15.3 °C | 30.4 °C | 2.03 mm |
| October | 11.9 °C | 24.9 °C | 17.02 mm |
| November | 7.6 °C | 17.7 °C | 32.26 mm |
| December | 4.6 °C | 12.9 °C | 67.06 mm |
| Annual | 10.4 °C | 22.6 °C | 372.12 mm |
| Average First Frost Date | Nov. 21 - Nov. 30 |
| Average Last Frost Date | Mar. 1 - Mar. 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 |