Geyserville, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 7 °C (low) to 22.8 °C (high). Annual precipitation averages 1009.9 Millimeters. Geyserville is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Feb. 11 - Feb. 20 through the first frost around Dec. 1 - Dec. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 3.2 °C | 14.4 °C | 202.69 mm |
| February | 3.9 °C | 16.4 °C | 203.45 mm |
| March | 5.1 °C | 18.4 °C | 141.99 mm |
| April | 6.2 °C | 21.1 °C | 68.83 mm |
| May | 8.2 °C | 24.6 °C | 36.07 mm |
| June | 10.3 °C | 28.7 °C | 6.86 mm |
| July | 11.3 °C | 30.2 °C | 0.76 mm |
| August | 11.1 °C | 30.8 °C | 1.52 mm |
| September | 9.9 °C | 30.1 °C | 3.81 mm |
| October | 7.6 °C | 25.5 °C | 45.97 mm |
| November | 4.7 °C | 18.8 °C | 99.57 mm |
| December | 2.9 °C | 14.3 °C | 198.37 mm |
| Annual | 7 °C | 22.8 °C | 1009.89 mm |
| Average First Frost Date | Dec. 1 - Dec. 10 |
| Average Last Frost Date | Feb. 11 - Feb. 20 |
| Average Days With Frost | 10-20 Days |
| Plant Hardiness Zone | Zone 9a : -6.7°C to -3.9°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 |