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Frost Dates for Denver, Colorado, United States of America

Coordinates: 39.739, -104.984

Growing Season

The last spring air frost in Denver, Colorado, United States of America typically occurs around May 18, and the first autumn air frost around Sep 10. This gives a frost-free growing season of approximately 115 days.

USDA Hardiness Zone

This location falls in USDA Hardiness Zone 6a, where the average annual extreme minimum temperature is -23.3 to -20.6°C (-10 to -5°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 -7°C (19°F). The warmest month is July, 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 18 (last spring) to Sep 10 (first autumn). Light ground frost (-1°C / 30°F): May 8 (last spring) to Sep 18 (first autumn). Hard ground frost (-2°C / 28°F): Apr 22 (last spring) to Oct 2 (first autumn).

We predict your growing zone to be approximately ...

USDA Growing Zone: USDA Growing Zone - 6a

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

Current Risk Level: Hard Ground Frost possible

for today based on past data only.

We predict a frost free growing season at your location from May 18 to Sep 10, which provides approximately 114 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 May 8 to Sep 18, which provides a total of 133 days for growing.

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