Mille Lacs Lake Water Temperature
Mille Lacs Lake in Mille Lacs County, Minnesota averages about 72°F at the surface in summer — warmest in Aug (~78°F) and coldest in May (~57°F). These are typical values by month, not a live reading.
Typical water temperature by month
Typical surface water temperature by month, from 29 field readings (2022–2025) via the EPA Water Quality Portal. Months with too few readings are left blank.
Is Mille Lacs Lake warm enough to swim?
Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Want more than temperature? Mille Lacs Lake scored C on water quality — clarity, algae, phosphorus, depth, fish species, and swimming safety, all on one report card.
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Frequently asked questions
What is the water temperature of Mille Lacs Lake?
Mille Lacs Lake has a typical summer surface temperature of about 72°F. It is usually warmest in August (around 78°F) and coldest in May (around 57°F). These are typical values by month from 29 EPA Water Quality Portal field readings (2022–2025), not a live reading.
When is Mille Lacs Lake warmest?
Surface water at Mille Lacs Lake is typically warmest in August, reaching about 78°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 Mille Lacs Lake warm enough to swim?
At its typical summer peak of about 72°F, Mille Lacs Lake rates as "comfortable" for swimming. Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Where does this Mille Lacs Lake 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 — 29 readings from 1 monitoring station between 2022 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.