Sunfish Lake Water Temperature
Sunfish Lake in Washington County, Minnesota averages about 76°F at the surface in summer — warmest in Jul (~80°F) and coldest in May (~56°F). These are typical values by month, not a live reading.
Typical water temperature by month
Typical surface water temperature by month, from 46 field readings (2011–2025) via the EPA Water Quality Portal. Months with too few readings are left blank.
Is Sunfish Lake warm enough to swim?
Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Want more than temperature? Sunfish Lake scored B 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 ~63°F
Summer average ~74°F
Summer average ~78°F
Summer average ~68°F
Summer average ~73°F
Summer average ~70°F
Explore water temperatures
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Frequently asked questions
What is the water temperature of Sunfish Lake?
Sunfish Lake has a typical summer surface temperature of about 76°F. It is usually warmest in July (around 80°F) and coldest in May (around 56°F). These are typical values by month from 46 EPA Water Quality Portal field readings (2011–2025), not a live reading.
When is Sunfish Lake warmest?
Surface water at Sunfish Lake is typically warmest in July, reaching about 80°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 Sunfish Lake warm enough to swim?
At its typical summer peak of about 76°F, Sunfish Lake rates as "comfortable" for swimming. Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Where does this Sunfish 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 — 46 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.