May Climate Summary

May Precipitation Highlights:

• The first half of May was exceptionally dry for much of the area.  A trend to a more active weather pattern towards the end of the month brought beneficial rain to parts of the region; however many locations ended up 1-3 inches below normal.  Severe weather was low for the season, and early-season remnants from Tropical Storm Alberto affected parts of central and eastern Illinois on the 30th.
  • May 15: A slow-moving cold front triggered widely scattered strong to severe thunderstorms across south-central Illinois during the afternoon.  The most significant cell formed over southern Macon County, then tracked SE across portions of Moultire, Coles, and Clark counties.  This particular storm downed numerous trees, large tree branches, and power lines in Sullivan and Mattoon, and overturned 3 semis on I-70 near Martinsville.  The Mattoon Airport measured a wind gust of 71 mph as the storm blew through.  Other cells impacted portions of Christian, Sangamon, and Dewitt counties with strong winds and heavy rain.  Due to the very slow movement of the storms at only 10-20 mph, 1 to 3 inch amounts of rain fell in a short period of time, creating flash flooding in a few locations.
     

  • ​May 30: The remnants of Tropical Storm Alberto tracked northward along the Illinois/Indiana border. Widespread moderate rain fell east of I-57 through mid-afternoon, with total rainfall amounts of 1.50 - 2.00".  Further northwest, a persistent band of moderate to heavy rain developed overnight into the early morning near the Illinois River.  This band dropped impressive rainfall amounts of 2 to 4 inches, with localized amounts as much as 5 inches from just northwest of Springfield northward to near Peoria and Henry.  This caused flash flooding in portions of Tazewell, Woodford, and Marshall counties.  
     

May Precipitation	May Precipitation Departure from Normal

May Temperature Highlights:

• Just a month after March-like temperatures prevailed in April, summer heat quickly moved in and June level heat dominated central and southeast Illinois for May.  A strong upper level ridge displaced the main storm track, and more typical spring temperatures, to the north.  As a result most days saw highs in the 80s or 90s, breaking many daily records.  This produced the warmest May on record for many sites, including those with long station histories such as Peoria, Springfield, Urbana, and Lincoln.  The heat was relentless, with most sites reporting zero days with below normal temperatures.  This has not previously been observed in May, through the climate record.   
   

May Mean Temperature	May Temperature Departure from Normal

May Climate Data:

The following links are the monthly and seasonal 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 the city.

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

Climate data for other cities is available at http://w2.weather.gov/climate/xmacis.php?wfo=ilx