Exeter, California has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 10 °C (low) to 24.9 °C (high). Annual precipitation averages 289 Millimeters. Exeter 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 | 3.3 °C | 13.8 °C | 55.88 mm |
| February | 4.8 °C | 16.9 °C | 49.02 mm |
| March | 6.7 °C | 20.3 °C | 49.78 mm |
| April | 8.4 °C | 23.3 °C | 28.7 mm |
| May | 11.9 °C | 28.1 °C | 11.68 mm |
| June | 15.2 °C | 32.8 °C | 3.3 mm |
| July | 18.4 °C | 35.8 °C | 0.51 mm |
| August | 17.5 °C | 35.3 °C | 0 mm |
| September | 14.9 °C | 32.6 °C | 2.03 mm |
| October | 10.3 °C | 26.4 °C | 13.46 mm |
| November | 5.6 °C | 19.2 °C | 26.42 mm |
| December | 2.7 °C | 13.8 °C | 48.26 mm |
| Annual | 10 °C | 24.9 °C | 289.04 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 | BSk - Cold Semi-Arid Climate |