August Weather Summary

Overview

The average temperature for the month of August was 1-2 degrees below normal for central and southeast IL. However, the first half of the month featured afternoon temperatures at or above normal with another wave of some very warm to hot temperatures again from the 15th through the 19th before a couple of strong cold fronts brought some fall-like temperatures to our area to during the period from the 20th through the 29th. Overnight lows dropped to the upper 40s to lower 50s during this late August "cool snap". Rainfall for the month averaged below normal across most of the area with several potent weather systems for August bringing scattered strong to severe storms to the area. (Refer to the August temp and precip maps below).

• August 1-7: Temperatures overall averaged below normal during this time frame with below normal rainfall across the north, while rainfall averaged above normal across the south. A cold front moved across the area on the 2nd and 3rd of the month spawning strong to severe storms with the majority of the active storms staying to our north.  
   
• August 8-14: Heaviest rainfall during this period concentrated over parts of west central Illinois, with precipitation amounts a bit below normal over southeast Illinois. Temperatures averaged close to normal with a small area from Peoria to Bloomington that trended above normal during the second week of August.
   
• August 15-21: This was by far the most active week of the month, at least for severe storms, as a potent upper level storm system and surface cold front affected the area. Rainfall during this time frame averaged above normal except for a small area of extreme southeast Illinois where below normal precipitation was found. Temperatures for the most part were closer to where they should be for the third week of August, with only a small area of the far north seeing above normal temperatures, while areas over far southeast Illinois were trending a bit below normal. Severe storms, including one weak tornado near Mackinaw, pushed across the area on the 18th accompanied by reports of damaging straight line winds, large hail and isolated reports of heavy rainfall. 
   
• August 22-31: Another strong cold front moved across the area on the 23rd, however, unlike the strong front that pushed through the Midwest about a week earlier, the timing of the frontal passage across our area was not favorable for widespread severe storms. In addition, the deeper moisture ahead of this front was still south of our region, thanks in part to the previous frontal passage that pushed the tropical air mass well to our south as it plowed through our area about 3 to 4 days ago. The cold front was tracking across our area during the morning and early afternoon hours with storms not redeveloping until later in the afternoon, and mainly to our east.  
   

  August Temperature Maps

AUGUST PRECIPITATION MAPS

Climate Data

The table below summarizes August 2015 rainfall 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.
 

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.

• Peoria -- Peoria International Airport
• Springfield -- Abraham Lincoln Capital Airport
• Lincoln -- Lincoln NWS office
• Champaign -- University of Illinois - Willard Airport
• Decatur -- Decatur Airport
• Lawrenceville -- Lawrenceville-Vincennes International Airport
• Mattoon -- Coles County Airport

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