A rare frigid storm charged through Texas and the northern Gulf Coast on Tuesday, blanketing New Orleans and Houston with snow that closed highways, grounded nearly all flights and canceled school for more than a million students more used to hurricane dismissals than snow days.

By noon, the National Weather Service had reported about 4 inches of snow in New Orleans. The storm prompted the first ever blizzard warnings for several coastal counties near the Texas-Louisiana border, and snow plows were at the ready in the Florida Panhandle, according to the Associated Press.