Turtle Lake Deep Water Temperature
Turtle Lake Deep in Cook County, Minnesota averages about 73°F at the surface in summer — warmest in Aug (~75°F) and coldest in May (~51°F). These are typical values by month, not a live reading.
Typical water temperature by month
Typical surface water temperature by month, from 107 field readings (2011–2025) via the EPA Water Quality Portal. Months with too few readings are left blank.
Is Turtle Lake Deep warm enough to swim?
Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Want more than temperature? Turtle Lake Deep scored C on water quality — clarity, algae, phosphorus, depth, fish species, and swimming safety, all on one report card.
Water temperatures at nearby Minnesota lakes
Summer average ~72°F
Summer average ~67°F
Summer average ~73°F
Summer average ~73°F
Summer average ~72°F
Summer average ~70°F
Explore water temperatures
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Frequently asked questions
What is the water temperature of Turtle Lake Deep?
Turtle Lake Deep has a typical summer surface temperature of about 73°F. It is usually warmest in August (around 75°F) and coldest in May (around 51°F). These are typical values by month from 107 EPA Water Quality Portal field readings (2011–2025), not a live reading.
When is Turtle Lake Deep warmest?
Surface water at Turtle Lake Deep is typically warmest in August, reaching about 75°F. Lake surface temperature lags air temperature by several weeks, so the warmest water usually arrives in mid-to-late summer even though the hottest air can come earlier.
Is Turtle Lake Deep warm enough to swim?
At its typical summer peak of about 73°F, Turtle Lake Deep rates as "comfortable" for swimming. Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Where does this Turtle Lake Deep water temperature data come from?
Every temperature on this page is a typical (climatological) value computed from real surface-water field readings collected by state and federal agencies and published through the EPA Water Quality Portal — 107 readings from 2 monitoring stations between 2011 and 2025. They describe what is typical for each month, not the temperature right now.
About this data
Water temperatures are a climatology — the typical value for each month, averaged from real surface-water field readings collected by state and federal agencies and published through the EPA Water Quality Portal. They tell you what to expect, not the temperature at this moment. Actual conditions vary with recent weather, depth, and time of day.