Plymouth, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 8.3 °C (low) to 22.7 °C (high). Annual precipitation averages 783.3 Millimeters. Plymouth is located in USDA Plant Hardiness Zone 9b. The growing season typically runs from the last frost around Mar. 1 - Mar. 10 through the first frost around Dec. 1 - Dec. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 3 °C | 13 °C | 142.75 mm |
| February | 3.9 °C | 14.9 °C | 131.32 mm |
| March | 5.2 °C | 17.2 °C | 123.95 mm |
| April | 6.3 °C | 19.6 °C | 70.1 mm |
| May | 9.1 °C | 24.7 °C | 45.21 mm |
| June | 12.1 °C | 30.1 °C | 9.4 mm |
| July | 14.6 °C | 34.1 °C | 0.25 mm |
| August | 14.7 °C | 33.4 °C | 1.02 mm |
| September | 13.2 °C | 30.5 °C | 5.59 mm |
| October | 9.4 °C | 24.7 °C | 39.12 mm |
| November | 5.4 °C | 17.6 °C | 76.45 mm |
| December | 2.8 °C | 12.9 °C | 138.18 mm |
| Annual | 8.3 °C | 22.7 °C | 783.34 mm |
| Average First Frost Date | Dec. 1 - Dec. 10 |
| Average Last Frost Date | Mar. 1 - Mar. 10 |
| Average Days With Frost | 10-20 Days |
| Plant Hardiness Zone | Zone 9b : -3.9°C to -1.1°C |
| Plant Hardiness Zone - 2012 | Zone 9b : -3.9°C to -1.1°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |