Duluth, MN – Dense marine fog is expected to significantly reduce visibility across western Lake Superior overnight, with impacts likely to continue into Friday morning.
According to the National Weather Service in Duluth, fog will begin forming late Thursday evening, April 17, and intensify during the overnight hours. The most widespread and dense fog is anticipated a few hours before and after sunrise on Friday, April 18. Visibility may drop below one mile throughout coastal areas from Grand Marais to the Twin Ports.
A Dense Marine Fog Advisory is in effect for all western Lake Superior waters, including key ports such as Silver Bay, Taconite Harbor, and Saxon Harbor. Mariners and shoreline travelers should prepare for limited visibility, particularly between 3 a.m. and 9 a.m. Friday.
The fog results from warm rain falling onto the lake’s cooler surface, creating a low-lying vapor blanket. Officials recommend using fog lights, reducing speed while driving near the lake, and delaying non-essential marine activity until mid-morning Friday when conditions improve.
This marine fog pattern is common in early spring but can still pose risks for both commuters and recreational boaters. Residents should monitor local alerts and NOAA updates through Friday morning.
