Minnesota · St. Louis / Lake / Cook County
Lake Superior
Duluth · Two Harbors · Grand Marais
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"The largest freshwater lake on Earth by surface area — and famously, bracingly cold. Even in August, open-water surface temps on the North Shore often sit in the 50s. Locals swim anyway: Park Point in Duluth and shallow bays warm the most, and on a calm late-summer week the nearshore water can surprise you."
Seasonal pattern
When does Lake Superior warm up?
Lake Superior is deep (max depth 1332ft) and carries significant thermal inertia, so it warms slowly — surface temperatures typically don't reach comfortable swimming range until late June or early July. Spring-fed or alpine lakes stay cooler all summer. The live forecast above shows current conditions.
Field notes
About Lake Superior
- Largest freshwater lake in the world by surface area
- Coldest Great Lake — nearshore rarely passes the mid-60s even in August
- Park Point (Duluth) and shallow bays warm fastest on the Minnesota shore
- Cold-water safety matters here even in July — hypothermia risk is real
- Surface area
- 20,288,000 acres
- Max depth
- 1332 ft
- County
- St. Louis / Lake / Cook
- Water data
- Modeled estimate from air-temp trends