7 USDA Planting Zones in Southwest Washington: Olympia to Longview [Map]

Southwest Washington from Ashford to Yelm encompasses seven different USDA Planting Zones ranging from 6a to 9a, as declared by USDA in 2023. Winter temperatures here range from -10°F to 25°F (-23.3°C to -3.9°C).

The coldest zone here is USDA zone 6a (-10°F to -5°F / -23.3°C to -20.6°C) which covers parts of Skamania County. The warmest zone is USDA zone 9a (20°F to 25°F / -6.7°C to -3.9°C) which includes Camas, Washougal, and Wauna areas.

Most towns like Battle Ground, Brush Prairie, Castle Rock, and Centralia are in USDA zone 8b (15°F to 20°F / -9.4°C to -6.7°C) with winter lows of 15°F to 20°F.

Some areas here span multiple USDA zones like Clark County (7b-8a-8b-9a), Skamania County (6a-6b-7a-7b-8a-8b-9a), and Lewis County (6b-7a-7b-8a-8b).

Smaller towns like Kelso, Longview, Ridgefield, and Woodland are all in USDA zone 8b, while mountain communities like Trout Lake fall into the cooler zones 6b and 7a. So verify your USDA planting zone of Washington‘s Southwest region, using the interactive map or the USDA hardiness zones table provided below.

USDA Zones Map of Southwest Washington

Select or type your Southwest Washington’s location in selection box below, to find its USDA Growing zone.

Planting Zones Table of Southwest Washington

The 29 USDA hardiness zone locations in Southwest Washington are Ashford, Battle Ground, Brush Prairie, Camas, Castle Rock, Centralia, Chehalis, Clark County, Cowlitz County, Grand Mound, Kelso, Lewis County, Longview, Lyle, Olympia, Onalaska, Packwood, Ridgefield, Rochester, Ryderwood, Skamania County, Tenino, Trout Lake, Washougal, Wauna, White Salmon, Wilderness Rim, Woodland, and Yelm. The 29 USDA hardiness zone locations in Southwest Washington are listed below.