Right now (early May 2026) the lake is still very cold. Current readings range from about 34°F at Grand Portage up to roughly 46°F near Duluth, which is normal for this time of year — Lake Superior is one of the slowest Great Lakes to warm because of its volume and depth.
What to expect through summer:
- June: Nearshore areas typically climb into the upper 40s to mid-50s°F, while open water stays in the 40s.
- July: Shallow bays and protected shorelines can reach 55–62°F. Mid-lake stays cooler, often in the upper 40s to low 50s°F.
- August (peak): This is the warmest month, averaging around 65°F at the surface lake-wide. Sheltered bays (e.g., Chequamegon Bay, Munising, parts of the Apostle Islands) can briefly hit 68–72°F during calm, sunny stretches. Deeper offshore water typically stays below 50°F year-round.
- A strong wind shift can drop nearshore temps 15–20°F overnight via upwelling — something to keep in mind if you’re planning a swim.
For specific 2026 forecasts, the best live sources are:
- NOAA GLERL’s Lake Superior Nowcast/Forecast (updated continuously)
- GLISA’s seasonal water temperature outlook from the University of Michigan
- Local NWS marine forecasts for buoys at Duluth, Devils Island, Stannard Rock, and Whitefish Point
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