Downey, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 13.1 °C (low) to 23.9 °C (high). Annual precipitation averages 351 Millimeters. Downey is located in USDA Plant Hardiness Zone 10b.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 8.4 °C | 19.8 °C | 81.79 mm |
| February | 9.2 °C | 19.8 °C | 89.15 mm |
| March | 10.5 °C | 20.5 °C | 56.9 mm |
| April | 11.7 °C | 22.7 °C | 19.3 mm |
| May | 14 °C | 23.7 °C | 6.1 mm |
| June | 15.9 °C | 25.5 °C | 1.78 mm |
| July | 17.7 °C | 28.3 °C | 1.27 mm |
| August | 18.1 °C | 29.3 °C | 0.25 mm |
| September | 17.3 °C | 28.8 °C | 2.79 mm |
| October | 14.7 °C | 26.4 °C | 12.95 mm |
| November | 10.9 °C | 22.7 °C | 21.08 mm |
| December | 8.2 °C | 19.6 °C | 57.66 mm |
| Annual | 13.1 °C | 23.9 °C | 351.02 mm |
| Average First Frost Date | No Frost |
| Average Last Frost Date | |
| Average Days With Frost | Frost Free |
| Plant Hardiness Zone | Zone 10b : 1.7°C to 4.4°C |
| Plant Hardiness Zone - 2012 | Zone 10b : 1.7°C to 4.4°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |