July weather a month of extremes
Send a link to a friend
[August 05, 2011]
CHAMPAIGN -- July could be described as
a month of extremes for Illinois. Hot and humid weather was
persistent throughout the month. Meanwhile, heavy rains occurred in
parts of northern and southern Illinois, while central Illinois
struggled with dry weather, according to Jim Angel, state
climatologist, of the Illinois State Water Survey.
The statewide average temperature for July in Illinois was 80.1
degrees. That is 4.3 degrees above average and the sixth-warmest on
record (tied with 1955). The warmest July on record was 1936 with an
average of 83.1 degrees.
While the daytime temperatures were
impressive, it was the very warm nighttime temperatures that pushed
this July into the top 10 list.
Champaign-Urbana had the seventh-hottest July in terms of daytime
high temperatures but the second-hottest July in terms of nighttime
low temperatures. Why so hot, especially at night? The high humidity
levels prevented the night air from cooling off.
At least 38 sites reported temperatures reaching 100 degrees or
more. The highest temperature reported for July was 105 degrees at
Dixon Springs on July 13 and at Streator on July 25.
The statewide average rainfall for July in Illinois was 4.12
inches, only 0.29 inches above average. However, rainfall across the
state varied widely from too dry to too wet.
Rainfall amounts in the northern third of the state were
impressive, with widespread areas in excess of 6 to 8 inches. The
heaviest rains fell around Galena, with one site reporting a monthly
rainfall total of 19.21 inches, while another nearby site reported
Elizabeth reported 16.74 inches, Freeport 12.08 inches, and Mount
Carroll reported 11.33 inches of rain. Chicago O’Hare airport had a
July rainfall total of 11.15 inches, their wettest July on record,
thanks largely to the 6.86 inches that fell in three hours on July
[to top of second column]
The middle third of Illinois was exceptionally dry. Some of the
smaller rainfall totals for July were just south and west of the
heavy rainfall in northwest Illinois. One of the drier sites was
Aledo, with only 0.55 inches of rain. Amounts of only 1 to 2 inches
were common in central Illinois.
It was wet in the southern third of Illinois, where amounts of 4
to 8 inches or more were common. The largest July rainfall total was
at Du Quoin with 8.88 inches.
The Illinois State Water
Survey at the University of Illinois at Urbana-Champaign, a
division of the Prairie Research Institute, is the primary agency in
Illinois concerned with water and atmospheric resources.
[Text from file received from
State Water Survey]