July Weather Summary -- Unusually Hot and Humid

July will be remembered for the excessive length of heat and humidity that plagued the region much of the month. 


July average high temperaturesHigh temperatures of 90 degrees or higher were common over the area.  Some specific counts for area cities:

Decatur (airport) -- 19 days.
Effingham -- 21 days.
Jacksonville -- 19 days.
Lawrenceville (airport) -- 25 days.
Lincoln -- 13 days.
Normal -- 20 days.
Olney -- 18 days.
Peoria -- 17 days.
Springfield -- 21 days.
Urbana -- 18 days.

Some highlights in the area:

* Central and southeast Illinois was under an Excessive Heat Warning from July 17th through the 24th.  Heat index values during this period were occasionally as high as 115 degrees.

* Springfield observed 14 consecutive days with highs of 90 or above, from the 16th through the 29th.  This was the longest such streak since 1955, but over a week short of the record (22 days).

* Urbana reported 3 days with highs of 100 or higher, after having not reached the century mark since July 1995.

* The Decatur airport reported two days (20th and 22nd) where the low temperature failed to reach below 80 degrees.

* The average high temperature was at least 90 degrees over most locations south of I-72, and in the upper 80s to the north. 

 

With a persistent dome of upper level high pressure, storm tracks were frequently steered further to the north.  Indeed, record July rainfall occurred in Chicago and Dubuque, IA.  As a result, rainfall over most of central Illinois was only a quarter to half of what should have occurred:

July rainfall percentage of normal

Only areas from Flora east to Lawrenceville saw widespread above-normal rainfall.  Some of the heavier totals included Flora with 5.11 inches (including 2.73" on the 8th) and Olney with 5.05 inches (including 1.29" on the 8th and 1.69" on the 13th).  Just west of Birds, in northern Lawrence County, over 5.5 inches fell in a few hours on the 24th.  Further north, some rainfall of 1 to 2.5 inches occurred early in the morning of the 29th north of Peoria and Galesburg.

Here are links to specific climate summaries for area cities.  The summaries for Peoria, Springfield, and Lincoln are the official data for those locations.  For the remaining locations, they are supplemental, meaning another site in the area is the official climate station.

 



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