Ione, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 9.5 °C (low) to 23.6 °C (high). Annual precipitation averages 622.3 Millimeters. Ione is located in USDA Plant Hardiness Zone 9b. The growing season typically runs from the last frost around Feb. 11 - Feb. 20 through the first frost around Dec. 21 - Dec. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 3.9 °C | 13.3 °C | 119.13 mm |
| February | 5.2 °C | 16.1 °C | 109.22 mm |
| March | 6.8 °C | 18.8 °C | 93.98 mm |
| April | 8.1 °C | 21.9 °C | 56.13 mm |
| May | 10.8 °C | 26.3 °C | 38.1 mm |
| June | 13.7 °C | 30.9 °C | 5.59 mm |
| July | 15.4 °C | 34.3 °C | 0.51 mm |
| August | 15.3 °C | 34.1 °C | 2.03 mm |
| September | 14 °C | 31.1 °C | 5.33 mm |
| October | 10.4 °C | 25.3 °C | 25.4 mm |
| November | 6.2 °C | 18.2 °C | 60.2 mm |
| December | 3.8 °C | 13.4 °C | 106.68 mm |
| Annual | 9.5 °C | 23.6 °C | 622.3 mm |
| Average First Frost Date | Dec. 21 - Dec. 31 |
| Average Last Frost Date | Feb. 11 - Feb. 20 |
| 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 |