Ione, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 49.1 °F (low) to 74.5 °F (high). Annual precipitation averages 24.5 Inches. 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 | 39.1 °F | 55.9 °F | 4.69 in. |
| February | 41.3 °F | 60.9 °F | 4.3 in. |
| March | 44.2 °F | 65.8 °F | 3.7 in. |
| April | 46.6 °F | 71.4 °F | 2.21 in. |
| May | 51.5 °F | 79.3 °F | 1.5 in. |
| June | 56.6 °F | 87.6 °F | 0.22 in. |
| July | 59.8 °F | 93.7 °F | 0.02 in. |
| August | 59.6 °F | 93.3 °F | 0.08 in. |
| September | 57.2 °F | 88.0 °F | 0.21 in. |
| October | 50.7 °F | 77.5 °F | 1.0 in. |
| November | 43.2 °F | 64.8 °F | 2.37 in. |
| December | 38.8 °F | 56.2 °F | 4.2 in. |
| Annual | 49.1 °F | 74.5 °F | 24.5 in. |
| 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 : 25°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 9b : 25°F to 20°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |