Montclair, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 11.3 °C (low) to 25.6 °C (high). Annual precipitation averages 410 Millimeters. Montclair is located in USDA Plant Hardiness Zone 10a.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 6.7 °C | 19.5 °C | 91.19 mm |
| February | 7.1 °C | 19.7 °C | 107.44 mm |
| March | 8.3 °C | 21.4 °C | 67.06 mm |
| April | 9.6 °C | 23.6 °C | 19.3 mm |
| May | 11.9 °C | 25.6 °C | 10.67 mm |
| June | 14.1 °C | 29 °C | 2.79 mm |
| July | 16.7 °C | 32.6 °C | 1.52 mm |
| August | 17.2 °C | 33.7 °C | 0.51 mm |
| September | 16.1 °C | 32.1 °C | 3.3 mm |
| October | 12.9 °C | 27.6 °C | 17.78 mm |
| November | 8.9 °C | 23.2 °C | 23.62 mm |
| December | 6.4 °C | 19 °C | 64.77 mm |
| Annual | 11.3 °C | 25.6 °C | 409.95 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 |