frostdates.com

Turbo charge your gardening, homesteading and horticultural powers with our international frost date and growing zone calculator

Frost Dates for Portland, Oregon, United States of America

Coordinates: 45.524, -122.675

Growing Season

The last spring air frost in Portland, Oregon, United States of America typically occurs around May 19, and the first autumn air frost around Oct 2. This gives a frost-free growing season of approximately 136 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 January, with an average low of 2°C (36°F). The warmest month is August, with an average high of 29°C (84°F).

Frost Risk Breakdown

Frost dates at three temperature thresholds: Air frost (0°C / 32°F): May 19 (last spring) to Oct 2 (first autumn). Light ground frost (-1°C / 30°F): Apr 26 (last spring) to Oct 19 (first autumn). Hard ground frost (-2°C / 28°F): Mar 9 (last spring) to Nov 20 (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: Unlikely (Safest)

for today based on past data only.

We predict a frost free growing season at your location from May 19 to Oct 2, which provides approximately 135 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 26 to Oct 19, which provides a total of 176 days for growing.

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec