Norco, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 10.8 °C (low) to 26.2 °C (high). Annual precipitation averages 264.9 Millimeters. Norco is located in USDA Plant Hardiness Zone 10a.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 6.1 °C | 20.1 °C | 53.09 mm |
| February | 6.4 °C | 20.3 °C | 70.61 mm |
| March | 7.8 °C | 22.1 °C | 43.18 mm |
| April | 9.2 °C | 24.1 °C | 14.48 mm |
| May | 11.8 °C | 26.2 °C | 5.33 mm |
| June | 14 °C | 29.7 °C | 1.02 mm |
| July | 16.4 °C | 33.2 °C | 1.78 mm |
| August | 16.8 °C | 34.2 °C | 1.02 mm |
| September | 15.6 °C | 32.7 °C | 3.05 mm |
| October | 12.1 °C | 28.3 °C | 8.89 mm |
| November | 7.9 °C | 23.8 °C | 16.26 mm |
| December | 5.4 °C | 19.8 °C | 46.23 mm |
| Annual | 10.8 °C | 26.2 °C | 264.94 mm |
| Average First Frost Date | Jan. 21 - Jan. 31 |
| 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 9b : -3.9°C to -1.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |