MINNEAPOLIS (AP) - Thick fog has been causing delays at Minneapolis-St. Paul International Airport.

Airport spokesman Pat Hogan did not have numbers from the airlines early Monday, but he said planes had to taxi much more slowly because the tower could not see them. He said the situation was starting to improve around 8:30 a.m., but delays are expected to continue through much of the morning.

The National Weather Service issued dense fog advisories stretching north from the Iowa border through Albert Lea and Rochester, to the Twin Cities and beyond.

Visibilities were below 100 feet in some areas. Some school districts started classes late because of the fog.