Mercer County, Illinois · Frost dates

Mercer County frost dates.

First-frost, last-frost, and growing-season length for Mercer County, Illinois. Sourced from NOAA 1991-2020 Climate Normals.

Data confidence: high · USDA zone: 6a

32°F — light freeze

Last spring frost

10%
05-06
20%
05-02
50%
04-22
80%
04-12
90%
04-07

First fall frost

10%
10-06
20%
10-12
50%
10-19
80%
10-27
90%
10-31

28°F — killing freeze

Last spring freeze

10%
04-29
20%
04-22
50%
04-11
80%
04-02
90%
03-29

First fall freeze

10%
10-16
20%
10-20
50%
10-29
80%
11-05
90%
11-10

Growing season length (days, 28°F threshold)

Short year
170
Median
201
Long year
226

Source NOAA station

ALEDO, IL US

0.6 mi · 30 yrs of record (19912020) · 730 ft elev.

Data from ALEDO, IL US, 0.6 miles away with 30-year NOAA record (1991-2020).

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