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Frost Dates for Seattle, Washington, United States of America

Coordinates: 47.606, -122.331

Growing Season

The last spring air frost in Seattle, Washington, United States of America typically occurs around May 12, and the first autumn air frost around Oct 3. This gives a frost-free growing season of approximately 144 days.

USDA Hardiness Zone

This location falls in USDA Hardiness Zone 8b, where the average annual extreme minimum temperature is -9.4 to -6.7°C (15 to 20°F). This zone rating helps gardeners determine which perennial plants are likely to survive winter.

Temperature Overview

The coldest month is February, with an average low of 2°C (36°F). The warmest month is August, with an average high of 26°C (79°F).

Frost Risk Breakdown

Frost dates at three temperature thresholds: Air frost (0°C / 32°F): May 12 (last spring) to Oct 3 (first autumn). Light ground frost (-1°C / 30°F): Apr 19 (last spring) to Oct 24 (first autumn). Hard ground frost (-2°C / 28°F): Feb 20 (last spring) to Jan 13 (first autumn).

We predict your growing zone to be approximately ...

USDA Growing Zone: USDA Growing Zone - 8b

... and the frost data for your area is ...

Current Risk Level: Light Ground Frost possible

for today based on past data only.

We predict a frost free growing season at your location from May 12 to Oct 3, which provides approximately 143 frost free days.

For the less tender plants, or if you are planning to protect your plants with fleece etc, your growing season could stretch from Apr 19 to Oct 24, which provides a total of 188 days for growing.

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