Early summer-like weather meant early blooms in area yards and early planting for eager gardeners, but a return to more seasonable cool temperatures Thursday night could be bad news for those early bloomers.
The National Weather Service says frost is possible Thursday night and Friday morning across northern Illinois and northwest Indiana, putting cold-sensitive plants in jeopardy. The coldest temperatures are expected in areas inland from Lake Michigan.
Lows are expected to be near 29 around Rockford, and 32 across much of the area, while only dropping to 35 along the Chicago lakefront and 38 in Gary. Temperatures could drop into the high 20s across the Fox River Valley and points west, the weather service said.
A freeze warning is in effect across the area from 1 a.m. to 8 a.m. Friday.
A cool area of high pressure across Ontario was building southward across the Great Lakes on Thursday and a cool, dry air mass accompanying the high pressure will combine with mostly clear skies and winds gusting to 30 mph to produce “a good potential for freezing temperatures,” the weather service said in a frost alert.
Freezing temperatures are not uncommon in Chicago in early April, but record highs in March brought an early growing season, and many plants are sprouting or blooming four to six weeks early, the weather service said.
These often cold-sensitive plants will be “extremely vulnerable to being damaged or even killed” if a hard freeze occurs.
Gardeners are warned to take all necessary precautions to protect any sensitive vegetation.
Friday will be sunny with highs in the lowers 50s, and Friday night will again be cool, with lows in the mid 30s,
before temperatures rebound into the mid-60s on Saturday.