Tenino, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 5.5 °C (low) to 16.2 °C (high). Annual precipitation averages 1404.4 Millimeters. Tenino is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 1.4 °C | 8.1 °C | 201.17 mm |
| February | 1.1 °C | 9.8 °C | 138.68 mm |
| March | 2.3 °C | 12.3 °C | 149.1 mm |
| April | 3.8 °C | 15.1 °C | 113.03 mm |
| May | 6.8 °C | 18.9 °C | 68.58 mm |
| June | 9.3 °C | 21.6 °C | 49.53 mm |
| July | 11.2 °C | 25.3 °C | 17.78 mm |
| August | 11.2 °C | 25.8 °C | 27.18 mm |
| September | 8.8 °C | 22.6 °C | 51.05 mm |
| October | 5.7 °C | 16.2 °C | 133.6 mm |
| November | 2.8 °C | 10.7 °C | 238.76 mm |
| December | 1.1 °C | 7.5 °C | 215.9 mm |
| Annual | 5.5 °C | 16.2 °C | 1404.36 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8b : -9.4°C to -6.7°C |
| Plant Hardiness Zone - 2012 | Zone 8a : -12.2°C to -9.4°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |