Oceano, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 9.9 °C (low) to 19.7 °C (high). Annual precipitation averages 386.1 Millimeters. Oceano is located in USDA Plant Hardiness Zone 10a.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 7.7 °C | 17.9 °C | 73.91 mm |
| February | 7.9 °C | 17.9 °C | 85.85 mm |
| March | 8.3 °C | 18.5 °C | 70.36 mm |
| April | 8.8 °C | 20.1 °C | 22.61 mm |
| May | 9.8 °C | 19.8 °C | 10.67 mm |
| June | 11.1 °C | 21.3 °C | 2.03 mm |
| July | 12.6 °C | 21.3 °C | 1.52 mm |
| August | 12.6 °C | 19.8 °C | 0.51 mm |
| September | 11.9 °C | 20.4 °C | 2.03 mm |
| October | 10.9 °C | 20.8 °C | 17.53 mm |
| November | 9.4 °C | 20.2 °C | 35.56 mm |
| December | 7.3 °C | 17.8 °C | 63.5 mm |
| Annual | 9.9 °C | 19.7 °C | 386.08 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 | Csb - Warm-Summer Mediterranean Climate |