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Frost Dates for Rialto, California, United States of America

Coordinates: 34.106, -117.369

Growing Season

The last spring air frost in Rialto, California, United States of America typically occurs around May 4, and the first autumn air frost around Oct 13. This gives a frost-free growing season of approximately 162 days.

USDA Hardiness Zone

This location falls in USDA Hardiness Zone 8a, where the average annual extreme minimum temperature is -12.2 to -9.4°C (10 to 15°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 5°C (41°F). The warmest month is August, with an average high of 35°C (95°F).

Frost Risk Breakdown

Frost dates at three temperature thresholds: Air frost (0°C / 32°F): May 4 (last spring) to Oct 13 (first autumn). Light ground frost (-1°C / 30°F): Apr 10 (last spring) to Oct 29 (first autumn). Hard ground frost (-2°C / 28°F): Feb 12 (last spring) to Dec 15 (first autumn).

We predict your growing zone to be approximately ...

USDA Growing Zone: USDA Growing Zone - 8a

... 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 4 to Oct 13, which provides approximately 161 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 10 to Oct 29, which provides a total of 202 days for growing.

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