A flash flood watch was posted for Boone and adjacent counties from noon Wednesday through Thursday morning.
Rain from tropical storm Hermine is likely to cause wet weather this week for Missouri.
Hurricane Earl is approaching North Carolina's Outer Banks and might reach the coast of Massachusetts shortly.
The Category 4 storm is expected to scrape Cape Hatteras, Long Island and eastern New England.
Officials hope the 800 or so local residents will follow tourists off the Outer Banks island before the hurricane strikes.
The hurricane is forecast to potentially brush North Carolina late Thursday before heading parallel to land up the East Coast.
The East Coast of the U.S. could see some rain from the storm later this week.
The 2011 edition of the Farmers' Almanac calls for a brutal winter season in Missouri, with plenty of snow and cold temperatures through March.
Schools without air conditioning will dismiss early Friday. All other schools will remain in session all day.
The death of a 74-year-old St. Louis woman is being blamed on the heat, bringing to 10 the number of suspected hot weather-related deaths in Missouri.
Heavy recent rain in Iowa sent the Mississippi back above flood stage as far south as Lincoln County, Mo. Farmland is flooded in many areas, and a few roads are closed.
Iowa State University football players were stacking sandbags around the football stadium Wednesday, and Interstate 35 was closed just south of Ames.
The excessive heat warning issued Monday has been extended until 9 p.m. Friday, according to the National Weather Service.
The extreme temperatures are expected to last all week.
An excessive heat warning for parts of Missouri and Illinois, including Columbia, will be in effect until late Thursday.
The Jackson County medical examiner was investigating the latest suspected heat death. No details have been released on any of the victims.
Columbia is under an excessive heat warning, according to the National Weather Service.
A heat advisory was issued for Columbia for Tuesday and Wednesday.
The oil well cap will stay closed despite evacuations from the Deepwater Horizon site during a tropical storm.
Strong thunderstorms brought heavy rain and flash flooding to parts of Missouri, Illinois and Iowa on Tuesday. The worst damage appears to be in Hannibal.