Duluth, MN – Dangerous marine conditions are expected on Lake Superior beginning Wednesday and continuing into the weekend, with multiple rounds of gales and a significant risk of heavy freezing spray.
According to the National Weather Service Duluth, the first round of stronger winds is expected Wednesday afternoon and evening, with gusts exceeding 34 knots for many nearshore and offshore locations. Gusty winds intensify overnight, with another surge of 30–40 knot gusts early Thursday morning.
By Thursday afternoon, winds shift northwesterly and strengthen further. Forecasters say there is a 30–60% chance of storm-force gusts up to 50 knots from Two Harbors to Grand Portage, especially Thursday afternoon and evening. These conditions may produce hazardous waves and severe reductions in visibility.
Cold air arriving behind Thursday’s front dramatically increases the risk of heavy freezing spray, especially Thursday night and Friday. The combination of subfreezing temperatures, strong winds, and high wave action will make conditions extremely dangerous for mariners, with rapid ice accumulation possible on vessels and infrastructure.
Additional rounds of gales are forecast Friday night into Saturday, mainly affecting the North Shore and offshore waters. Locations such as Grand Marais, Grand Portage, Outer Island, Stockton Island, and Saxon Harbor are all included in elevated-risk zones.
The strongest potential gusts outlined in the forecast table show sustained periods of 34–45 kt gales across most marine zones, with several intervals of 45–50 kt storm-force winds likely near the North Shore.
Mariners are urged to avoid travel during gale periods, monitor updated warnings, and prepare for rapidly deteriorating conditions through Saturday morning.
