Blue Lake Water Temperature
Blue Lake in Isanti County, Minnesota averages about 76°F at the surface in summer — warmest in Jul (~79°F) and coldest in Oct (~57°F). These are typical values by month, not a live reading.
Typical water temperature by month
Typical surface water temperature by month, from 154 field readings (2016–2025) via the EPA Water Quality Portal. Months with too few readings are left blank.
Is Blue Lake warm enough to swim?
Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Want more than temperature? Blue Lake 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 ~78°F
Summer average ~75°F
Summer average ~75°F
Summer average ~74°F
Summer average ~76°F
Summer average ~74°F
Explore water temperatures
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Frequently asked questions
What is the water temperature of Blue Lake?
Blue Lake has a typical summer surface temperature of about 76°F. It is usually warmest in July (around 79°F) and coldest in October (around 57°F). These are typical values by month from 154 EPA Water Quality Portal field readings (2016–2025), not a live reading.
When is Blue Lake warmest?
Surface water at Blue Lake is typically warmest in July, reaching about 79°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 Blue Lake warm enough to swim?
At its typical summer peak of about 76°F, Blue Lake rates as "comfortable" for swimming. Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Where does this Blue 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 — 154 readings from 2 monitoring stations between 2016 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.