July Weather Summary

Overview

July 2014 was one of the coolest Julys on record for much of central and southeast Illinois.  This persistently cool weather pattern was caused by a buckle in the jet stream around a deep upper level low pressure system north of the Great Lakes, which provided a northwesterly flow of air into the Midwest.  Typical summer time heat and humidity was absent, with only a day or two of 90+ degree highs for most locations.  The most significant bouts of cool air occurred on the 2-5th, 15-16, and 28-29.  During most of these days highs were in the 70s and lows were in the 50s.  Several record lows and record cool highs were set during these periods.  As is typical with summertime rainfall, rain amounts showed high variability across the region during the month.  Areas west of the Illinois River and southwest of a Jacksonville to Effingham line, generally saw below normal totals, while areas of east-central Illinois saw much above normal totals.  The higher totals were mainly the result of two heavy rain events on July 7-8 and 12-13.  While isolated severe weather was observed during the month, major severe weather outbreaks did not occur, primarily due to the unseasonably cool air in place. 

  • July 7-8 
     A weakening cold front triggered a broken line of strong thunderstorms along and south of the I-70 corridor during the afternoon of July 7th.  Due to the very warm and humid airmass ahead of the front, the storms were efficient rain-producers and also contained tremendous amounts of lightning.  A few of the cells created strong wind gusts and minor wind damage, particularly from parts of Marion County southeastward into Wayne County.  These storms gradually settled southward toward the Ohio River and dissipated during the evening.  Meanwhile, another round of thunderstorms quickly began to develop across northern Kansas into northern Missouri during the evening.  This storm complex gradually shifted into west-central Illinois toward midnight.  While the main push of severe weather associated with the complex generally remained across northern and central Missouri, one cluster of storms tracked into central Illinois overnight.  Locally heavy rainfall of between 1 and 2 inches was common along its path from Brown and Cass counties eastward to Logan County.  Some minor wind damage occurred in the city of Lincoln as these storms rolled through, with a few trees and tree branches being blown down.
  • July 12-13
    A cluster of slow-moving thunderstorms produced very heavy rainfall across portions of east-central Illinois during the morning of July 12th.  The heavy rain primarily occurred along and just east of a Pontiac to Monticello line, where many locations picked up between 3 and 5 inches in a short amount of time.  An observer in Champaign measured a whopping 5.18", while other reports northwest of Champaign suggested as much as 6 to 7 inches may have occurred in isolated spots near Mahomet.  The heavy rain caused localized flash-flooding, particularly in Champaign.  Elsewhere around central and southeast Illinois, rainfall was lighter and more scattered in nature.  In fact, areas along and southwest of a Vandalia to Flora line reported little or no rainfall during the period. 
  • July 26
    Scattered thunderstorms developed ahead of a cold front during the afternoon hours over western Illinois.  As the storms tracked east of I-55 by late afternoon they became severe, with isolated damaging wind gusts and locally heavy rain, from near Clinton east through Champaign, and into southern Vermilion County.  Downed trees and power lines were reported along the path of the strongest cluster of storms.  Another cluster of storms developed farther south near Mattoon, and produced isolated strong winds and locally heavy rain as it shifted southeast towards the Indiana border by early evening.
     

 Temperature and Precipitation Maps

 

 

 

  July Temp. Departure from normal

July Precip. Total

July Precip. % of normal 

 

Climate Data

The table below summarizes July 2014 precipitation and temperature, and departure from normal for selected cities across central and southeast Illinois.  Data from Peoria and Springfield are from ASOS sites, while others are from NWS Cooperative Observers.
 

Site Precipitation Departure from Normal Average Temp. Departure from Normal
Decatur

2.58" 

 -1.40"

 70.1

 -6.4 
Effingham

1.93" 

 -1.95 "

 71.3

 -5.8 
Galesburg

3.43" 

 -0.95"

 69.8 

 -4.8 
Jacksonville

2.27" 

 -1.68" 

 69.9

 -4.9
Lincoln

4.78" 

 -0.28" 

 68.6

 -6.4

Normal

5.65" 

 +1.49"

 69.2

 -5.2
Olney

5.74" 

 +1.41"

 70.8

 -5.6
Peoria

1.49" 

 -2.36"

 72.2

 -3.3
Springfield

2.53" 

 -1.41"

 71.6

 -4.2
Urbana

   8.70" **

 +4.00"

 69.8 

 -5.1

** Urbana - 5th wettest July since 1888


Links below are the monthly climate summaries for area cities. Only the summaries for Peoria, Springfield and Lincoln are considered "official", meaning they are the station of record for their respective locations. The other summaries are "supplemental", meaning another location in the area is the official climate station for that city.

Climate data for other area cities is available at http://www.nws.noaa.gov/climate/xmacis.php?wfo=ilx



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