Rosemead, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 12.8 °C (low) to 25.6 °C (high). Annual precipitation averages 415.3 Millimeters. Rosemead is located in USDA Plant Hardiness Zone 10a.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 8.2 °C | 20.7 °C | 95.5 mm |
| February | 8.8 °C | 20.7 °C | 108.97 mm |
| March | 10 °C | 21.8 °C | 69.34 mm |
| April | 11.4 °C | 24.5 °C | 22.61 mm |
| May | 13.8 °C | 25.4 °C | 9.91 mm |
| June | 15.8 °C | 28.1 °C | 3.05 mm |
| July | 17.7 °C | 30.9 °C | 0.76 mm |
| August | 18.1 °C | 32.1 °C | 0.25 mm |
| September | 17.2 °C | 31.4 °C | 3.56 mm |
| October | 14.4 °C | 28.1 °C | 14.99 mm |
| November | 10.6 °C | 23.8 °C | 19.81 mm |
| December | 7.7 °C | 20.2 °C | 66.55 mm |
| Annual | 12.8 °C | 25.6 °C | 415.3 mm |
| Average First Frost Date | Frost Rare |
| Average Last Frost Date | |
| Average Days With Frost | Frost Rare |
| 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 |