The Institute warns of slippery roads for all of Bohemia and western regions of Moravia. East Moravian locales near the Slovakian border are unaffected.
The most severe warnings have been issued for Southern Bohemia, including Písek, Tábor, České Budějovice, and Český Krumlov.
Sleet and dangerous roads have also been reported in the Vysočina region, according to iDnes.cz.
Winter weather is expected through this Thursday, with single-digit highs and average temperatures hovering around 0° Celsius in most localities.
Some precipitation including snowfall is also expected, especially in areas of higher elevation.
A mild warm front is in the forecast over the weekend, however, with highs nearing 10° Celsius.