CHICAGO (CBS) — The National Weather Service issued Tuesday a Frost Advisory for northern Illinois into Wisconsin from 1 a.m. to 8 a.m. Wednesday.

The National Weather Service in Chicago issued a Frost Advisory for Rockford, Belvidere, Woodstock, Waukegan, Oregon, Dixon, Dekalb, Aurora, Elgin, Wheaton, and Chicago.

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A Frost Advisory means that widespread frost is expected.

Temperatures are expected to hit the low to mid 30s, away from the more highly urbanized areas of the Chicago Metro Area where temperatures will be in the upper 30s, according to the NWS. The frost timing is expected late Tuesday night through sunrise Wednesday.

The Frost Advisory can impact sensitive outdoor plants. The NWS tells people to cover or move plants indoors to avoid frost damage.

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The last hard frost in Chicago was April 1, but if you’ve done some planting since then, Chicago Botanic Garden’s Boyce Tankersley said you may have to bring in some like tomatoes, peppers, eggplants and some hanging baskets. WBBM’s Lisa Fielding reports.

Tankersley said it’s best to be a little patient when planting anything else. He said end of May, begriming of June is the best time to plant each year in Chicago. Tulips, daffodils, and flowering trees should be fine and survive light frost, he said, but if you can’t move in your vulnerable plants, he recommends covering them with bubble wrap as not to disturb the bud.

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To keep up with the storm’s latest conditions and more, visit the CBS Chicago Weather page or download the CBS Chicago Weather app.