(CNN) -- A heat wave in parts of the Plains states and Midwest kept temperatures Monday as high as 20 degrees above normal, and it's likely to last until the end of the week.

Heat warnings and advisories are in effect for eight states: North Dakota, South Dakota, Nebraska, Illinois, Wisconsin, Iowa, Minnesota and Missouri.

The heat index in Iowa reached 110 degrees Monday afternoon, Iowa's Department of Public Health said, and it warned residents of the risk of heat-related illnesses. It said even young and healthy people could be affected if they are active in hot weather.

The high temperatures are forcing a number of school districts across the region to make changes to their schedules.

http://www.cnn.com/2013/08/26/us/midwest-heat/index.html?hpt=us_bn1