Atascadero, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 6.5 °C (low) to 23.3 °C (high). Annual precipitation averages 568 Millimeters. Atascadero 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. 11 - Dec. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 2.8 °C | 16.6 °C | 127.51 mm |
| February | 3.4 °C | 17.4 °C | 123.19 mm |
| March | 4.6 °C | 19.2 °C | 101.09 mm |
| April | 5.1 °C | 21 °C | 33.78 mm |
| May | 7.1 °C | 23.4 °C | 12.45 mm |
| June | 9.3 °C | 27.9 °C | 2.29 mm |
| July | 11.4 °C | 30.1 °C | 1.02 mm |
| August | 11.1 °C | 30.9 °C | 0.51 mm |
| September | 9.7 °C | 29.6 °C | 2.29 mm |
| October | 7.3 °C | 25.8 °C | 24.89 mm |
| November | 4.3 °C | 20.7 °C | 44.2 mm |
| December | 2.2 °C | 16.4 °C | 94.74 mm |
| Annual | 6.5 °C | 23.3 °C | 567.96 mm |
| Average First Frost Date | Dec. 11 - Dec. 20 |
| Average Last Frost Date | Feb. 11 - Feb. 20 |
| Average Days With Frost | 20-30 Days |
| Plant Hardiness Zone | Zone 9a : -6.7°C to -3.9°C |
| Plant Hardiness Zone - 2012 | Zone 9a : -6.7°C to -3.9°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |