Severe thunderstorms will slice southward into a zone of hot air from Kansas City to Springfield, Mo., Little Rock, Ark., Topeka and Wichita, Kan., and Tulsa, Okla., through the end of the week.
The storms bring the risk of damaging wind gusts, flash flooding, large hail, frequent lightning strikes and perhaps a few tornadoes.
It is possible the storms will organize into a squall line that travels hundreds of miles from northeastern Kansas to central Oklahoma and Arkansas into late Thursday night and early Friday.
People in the risk area for the severe storms should be prepared for rapidly changing weather conditions.
The storms have the potential to knock down trees and power lines, as well as cause significant property damage.
Meanwhile, many areas from northern Texas to the central Plains will have their hottest weather of the season so far. For some cities, Thursday will bring their first 100-degree reading this year. These cities include Oklahoma City, Little Rock, Tulsa and Dallas.
Avoid exercising or manual labor, if possible, during the afternoon when the sun is the strongest and temperatures are the highest.
If you must work outdoors in the heat, be sure to take frequent breaks and drink plenty of fluids.
Move indoors away from windows as storms approach.
Avoid parking in flood-prone areas.
Never attempt to drive through a flooded roadway. Doing so not only puts yourself and occupants at risk, but it also endangers your would-be rescuers.
If you can hear lightning, you are at risk for being struck, whether the sun is out, the storm is not heading directly at your or has recently passed by.
Hawaii will escape the worst, but not all of Guillermo's impacts as the tropical storm passes north of the islands Wednesday through Thursday.
A line of violent thunderstorms tore across Massachusetts, including the Boston area, Tuesday afternoon.
The Northeast will catch a break from heat and humidity for the remainder of the week.
Typhoon Soudelor in the western Pacific Ocean will remain a powerful tropical cyclone this week eventually threatening Taiwan and eastern China.
Two spectators were killed and at least another 32 people were injured Monday evening, as strong storms forced a circus tent to collapse in Lancaster, New Hampshire.
Public officials are in the process of eliminating Naegleria Fowleri, a brain-eating amoeba, from two drinking water supplies in Louisiana.
Casper, WY (1980)
39 degrees, broke 1974 record for the date by 9 degrees.
Norfolk, NE (1989)
Early morning thunderstorm brought sustained winds of 60 mph with gusts to 92 mph.
Southern California (1997)
Hurricane Guillerno produced 12 foot waves and strong rip currents. 1 person was killed and 3 others injured in the Newport Beach area.