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Is it safe to swim in Lake Superior today?

With over 31,700 square miles of surface area, Lake Superior is the largest freshwater lake in the world by surface area. Stretching from Minnesota to Michigan and partially into Canada, this vast body of water offers plenty of opportunities for swimming and water recreation. However, with its massive size comes significant risks. Before jumping into the frigid waters, it’s important to consider factors like water temperature, weather conditions, and water quality to determine if it’s safe to take a dip.

Water Temperature

One of the biggest dangers of swimming in Lake Superior is hypothermia due to the extremely cold water. Even in the summer, surface temperatures in the lake rarely exceed 55°F (13°C). At these temperatures, hypothermia can set in within 1–2 hours. Surprisingly, drowning deaths are uncommon, since the cold water quickly incapacitates swimmers before they can drown. Instead, hypothermia is the most common cause of death for swimmers in Lake Superior.

The water temperature can vary considerably depending on location and time of year. As we are currently mid-September, the average water temperature across Lake Superior is around 50–55°F (10–13°C). This is quite chilly for swimming! Certain areas, such as near river outlets, are slightly warmer at this time of year. However, you can expect the lake as a whole to be dangerously cold for most people without proper cold water swimming gear like wetsuits.

Weather Conditions

Beyond just the water temperature, the weather and wind conditions play a huge role in swimming safety on Lake Superior. The lake is notorious for its sudden storms, high winds, and large waves. Even on sunny days, winds can kick up quickly and create dangerous swimming conditions. Winds blowing along the long fetch of the lake can easily generate 10–15 foot waves.

Before swimming in Lake Superior, it is critical to check both the short and long term weather forecast. Look for any storms approaching, cold fronts coming through, or extended periods of wind out of the north or east. Swimming is safest on warm, calm, sunny days with light southerly winds. Always be prepared to get out of the water quickly if conditions deteriorate.

Water Quality

Thanks to its cold water, lack of anoxia, and limited agricultural runoff, Lake Superior has exceptionally clean and clear water compared to other Great Lakes. However, water quality can still vary depending on location and season.

Beaches sometimes temporarily close due to high bacteria levels from sewage overflows or other contamination sources after heavy rains. Some areas also experience occasional algae blooms. Check with local authorities to see if any water quality advisories are in effect for the area you plan to swim.

In general, water quality is best north of Duluth, away from major cities and upstream from river outlets. The clearest swimming areas are along the rugged northern shore in Minnesota and Ontario. Regardless, always avoid swimming for 2-3 days after major rainfall events, when contaminants are likely to wash into the lake.

Safety Precautions

If you do plan to brave the frigid waters, take proper safety precautions. Never swim alone, and only swim nearshore so you can quickly exit if needed. Wearing a wetsuit is highly recommended, even in summer, to guard against hypothermia. Have warm clothes, blankets, and spare dry clothes available. Avoid prolonged exposure, and get out of the water if you start shivering uncontrollably.

Of course, check swimming conditions beforehand, avoid swimming on cold, windy days or near passing storms. Wait several days after heavy rains for contamination to disperse. Avoid busy beaches and opt for less crowded, more secluded swimming spots to stay away from strong currents and waves created by lots of activity.

Never underestimate the power of Lake Superior. Many drowning deaths occur when people venture out too far from shore on inflatable toys or fall out of small boats. Always wear a lifejacket when boating or floating. Pay close attention to local warnings and weather forecasts through the day.

Location Recommendations

Certain areas of Lake Superior offer better swimming conditions than others. Here are some top picks:

  • Tettegouche State Park, MN – Clear water, secluded cobble beaches, and scenic cliffs; can be quite cold
  • Split Rock Lighthouse Beach, MN – South-facing sandy beach warms up fast; popular, so can get crowded
  • Twelvemile Beach, Ontario – More protected, shallow sandy beach stays warmer; beautiful turquoise waters
  • Marquette, MI – Sandy beach options near town; interior bays less prone to waves
  • Grand Marais, MN – Easy access from charming harbor town; mix of sand and rock

Avoid river outlets and beaches near cities, which tend to be murkier and more prone to contamination after rain events. Steer clear of isolated gravel or bedrock beaches with no easy exit point.

Current Lake Conditions

Checking current data for Lake Superior can give you a good idea of what to expect before heading out. Here are the latest observations:

Location Water Temp Wave Height Wind Speed
Duluth, MN 54°F 2 feet 10 mph NE
Marquette, MI 51°F 3 feet 15 mph N
Thunder Bay, Ont 50°F 1 foot 5 mph SE

Based on these observations, swimming conditions look fairly poor today across most of Lake Superior. Water temperatures remain cold for mid-September, ranging from 50-54°F. Wave heights up to 3 feet and northerly winds around 10-15 mph will make most areas rather choppy.

Thunder Bay seems the calmest currently, with light southerly winds and low wave heights. However, the water is still dangerously cold. Swimming anywhere in Lake Superior today would require an extremely thick wetsuit for protection against hypothermia.


In summary, Lake Superior offers stunning beauty and amazing swimming opportunities. However, its massive scale creates very unpredictable and often dangerous conditions. Hypothermia is a severe risk even in summer without proper cold water gear. Sudden storms, waves, and rip currents can also endanger swimmers.

Always thoroughly check the weather, wave forecasts, and current water conditions before swimming. Avoid cold, windy days and areas with recent heavy rainfall. Take precautions like swimming with a partner, wearing a wetsuit, and staying close to shore. With proper preparation for the unique challenges of Lake Superior, you can safely enjoy going for a dip in the legendary waters.