At least 22 deaths (most of them in traffic accidents) had been blamed on the storm since the waves of sleet and freezing rain started during the weekend.
The deaths include 15 in Oklahoma, four in Kansas, and three in Missouri.
Hundreds of thousands of homes and businesses had no electricity.
Officials in Missouri, Kansas and Oklahoma declared states of emergency. US President George W Bush declared an emergency in Oklahoma, ordering federal aid to supplement state and local response efforts.