Sunset Climate Zone Region

Western Washington

Zone 1a

Coldest mountain and intermountain areas of the contiguous states and Southwestern British Columbia

Zone 1b

Coldest Eastern Rockies and plains climate of Colorado, Wyoming, Montana, and Southern Alberta

Zone 2a

Cold mountain and intermountain areas

Zone 2b

Warmer-summer intermountain climate

Zone 3a

Mild areas of mountain and intermountain climates

Zone 3b

Mildest areas of intermountain climates

Zone 4

Cold-winter areas of the north coast and mild-winter areas of Alaska and British Columbia

Zone 5

Marine influence along the Northwest coast, Puget Sound, and South Vancouver Island

Zone 7

California

Zone 6

The Willamette and Columbia River Valleys

Zone 8

Cold-air basins of California

Zone 9

Thermal belts of California

Zone 10

High desert areas of Arizona and New Mexico

Zone 11

Medium to high desert of California and southern Nevada

Zone 12

Arizona

Zone 13

Low or subtropical desert areas

Zone 14

Northern California’s inland areas with some ocean influence

Zone 15

Chilly winters along the Coast Range

Zone 16

Central and Northern California Coast thermal belts

Zone 17

Marine effects in Southern Oregon, Northern and Central California

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