Atwater, California has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 9.5 °C (low) to 24.1 °C (high). Annual precipitation averages 324.9 Millimeters. Atwater 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. 1 - Dec. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 3.5 °C | 12.9 °C | 70.1 mm |
| February | 4.8 °C | 16.2 °C | 58.67 mm |
| March | 6.4 °C | 19.3 °C | 50.55 mm |
| April | 8.1 °C | 22.6 °C | 25.4 mm |
| May | 11.2 °C | 27.4 °C | 14.48 mm |
| June | 14.2 °C | 31.7 °C | 3.56 mm |
| July | 16.5 °C | 34.8 °C | 0.25 mm |
| August | 15.8 °C | 34.2 °C | 0 mm |
| September | 14.1 °C | 31.8 °C | 1.27 mm |
| October | 10.2 °C | 26.2 °C | 17.02 mm |
| November | 5.7 °C | 18.6 °C | 27.43 mm |
| December | 2.9 °C | 13.2 °C | 56.13 mm |
| Annual | 9.5 °C | 24.1 °C | 324.86 mm |
| Average First Frost Date | Dec. 1 - Dec. 10 |
| Average Last Frost Date | Feb. 11 - Feb. 20 |
| Average Days With Frost | 20-30 Days |
| Plant Hardiness Zone | Zone 9b : -3.9°C to -1.1°C |
| Plant Hardiness Zone - 2012 | Zone 9a : -6.7°C to -3.9°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |