Brea, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 12.3 °C (low) to 25.2 °C (high). Annual precipitation averages 357.1 Millimeters. Brea is located in USDA Plant Hardiness Zone 10a.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 7.8 °C | 20.4 °C | 83.31 mm |
| February | 8.3 °C | 20.5 °C | 95.5 mm |
| March | 9.6 °C | 21.7 °C | 53.85 mm |
| April | 10.8 °C | 24.2 °C | 17.53 mm |
| May | 13.3 °C | 25.1 °C | 7.62 mm |
| June | 15.2 °C | 27.1 °C | 2.03 mm |
| July | 17.3 °C | 30.2 °C | 1.02 mm |
| August | 17.6 °C | 31.4 °C | 0 mm |
| September | 16.7 °C | 30.7 °C | 3.3 mm |
| October | 13.9 °C | 27.9 °C | 13.46 mm |
| November | 10.2 °C | 23.6 °C | 19.81 mm |
| December | 7.4 °C | 20.1 °C | 59.69 mm |
| Annual | 12.3 °C | 25.2 °C | 357.12 mm |
| Average First Frost Date | No Frost |
| Average Last Frost Date | |
| Average Days With Frost | Frost Free |
| Plant Hardiness Zone | Zone 10a : -1.1°C to 1.7°C |
| Plant Hardiness Zone - 2012 | Zone 10a : -1.1°C to 1.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |