October brought record-breaking heat and cold and snow to Illinois
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[November 05, 2019]
temperatures soared from record-breaking heat during the first week
and fell to record-breaking cold at the month’s end in Illinois,
according to Illinois State Climatologist Trent Ford at the
University of Illinois’ Illinois State Water Survey. The first snow
of the season fell on or before Halloween.
The preliminary statewide October average temperature was 53.7
degrees, less than 1 degree below the 30-year normal.
Record-breaking high temperatures persisted from September into
early October. Average temperatures during the first four days
of October were 10 to 14 degrees above normal in the southeast
part of the state and 3 to 8 degrees above normal in the
Maximum temperatures broke 90 degrees and minimum temperatures
remained in the 70s for several days in southern Illinois.
Stations in Saint Clair and White Counties reached 96 degrees on
Between October 1 and 4, 46 daily high maximum temperature
records and 73 daily high minimum temperature records were
broken across Illinois, according to the National Centers for
Environmental Information (NCEI). Additionally, 9 stations broke
their all-time October high maximum temperature records, and 13
stations broke their all-time October high minimum temperature
In one particularly extreme event, the October 1 nighttime
minimum temperature at Kaskaskia Lock and Dam in Randolph County
was 72 degrees, 10 degrees above the previous daily record and 2
degrees above the all-time October minimum temperature record at
Seasonable temperatures were reported after the heat was broken
toward the end of the first week of October. Temperatures from
October 5 to 27 were near normal in eastern Illinois and between
3 and 6 degrees below normal for western Illinois.
Nearly all the state experienced the first fall frost event in
the second week of October. Nighttime minimum temperatures
dipped below 32 degrees as far south as Pope County and below 28
degrees in Warren and Jo Daviess Counties.
Temperatures between October 28 and 31 were 8 to 16 degrees
below normal. Similarly, 44 daily low maximum temperature
records and 8 daily low minimum temperature records were broken
across Illinois over the last four days of the month. Nighttime
minimum temperatures dropped below 30 degrees as far south as
The lowest minimum temperature observed in October was 14
degrees, both in Carroll County and Lee County on Halloween
night. This year was the coldest Halloween for 51 stations
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October precipitation was above normal for most of
the state and slightly below normal for west-central Illinois. The
statewide total precipitation in October was 5.20 inches,
approximately 2 inches more than the 30-year normal. Areas of far
northern and southern Illinois received over 6 inches of rainfall in
October, with isolated locations of more than 10 inches.
Stations in New Lenox in Will County and Riverwoods in Lake County
recorded over 12 inches of precipitation in October.
Significant rainfall helped improve drought conditions in southern
Illinois. The latest U.S. Drought Monitor map for October 29 shows
no drought in Illinois for the first time since early August.
Snow fell with some accumulation in northern and western Illinois.
Total snowfall accumulation over the last week of October ranged
from over 8 inches in northwestern Illinois to just over a tenth of
an inch as far south as Nokomis in Montgomery County.
The highest October snowfall total, 8.5 inches, was in Orangeville
in Jo Daviess County. Although late October is early for the first
snowfall in Illinois, this isn’t the first time it has happened.
Short-term 8- to 14-day outlooks from the Climate Prediction Center
show strong odds of below normal temperatures persisting into the
first couple of weeks of November. Below normal precipitation is
expected out to 14 days, as drier weather is likely to prevail
following the first winter storm of the season in Illinois.
Longer-term outlooks for November also show increased odds of below
normal temperatures and increased odds of above below normal
precipitation. Winter (December–February) outlooks show greater odds
of a wetter than normal winter.