Seaside, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 9.2 °C (low) to 17.8 °C (high). Annual precipitation averages 429.8 Millimeters. Seaside is located in USDA Plant Hardiness Zone 10a.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 6.4 °C | 15.6 °C | 89.92 mm |
| February | 6.9 °C | 15.7 °C | 88.14 mm |
| March | 7.4 °C | 16.2 °C | 67.31 mm |
| April | 7.9 °C | 16.7 °C | 31.5 mm |
| May | 9.6 °C | 17.9 °C | 11.68 mm |
| June | 10.9 °C | 18.7 °C | 2.79 mm |
| July | 12.2 °C | 19.2 °C | 1.02 mm |
| August | 12.6 °C | 19.7 °C | 0.76 mm |
| September | 11.9 °C | 20.4 °C | 1.78 mm |
| October | 10.2 °C | 20.2 °C | 17.53 mm |
| November | 7.9 °C | 17.8 °C | 40.13 mm |
| December | 6.1 °C | 15.6 °C | 77.22 mm |
| Annual | 9.2 °C | 17.8 °C | 429.78 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 9b : -3.9°C to -1.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |