Lost Lake Water Temperature
Lost Lake in Cass County, Minnesota averages about 74°F at the surface in summer — warmest in Jul (~78°F) and coldest in May (~63°F). These are typical values by month, not a live reading.
Typical water temperature by month
Typical surface water temperature by month, from 51 field readings (2011–2024) via the EPA Water Quality Portal. Months with too few readings are left blank.
Is Lost Lake warm enough to swim?
Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Want more than temperature? Lost Lake scored A 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 Lost Lake?
Lost Lake has a typical summer surface temperature of about 74°F. It is usually warmest in July (around 78°F) and coldest in May (around 63°F). These are typical values by month from 51 EPA Water Quality Portal field readings (2011–2024), not a live reading.
When is Lost Lake warmest?
Surface water at Lost Lake is typically warmest in July, 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 Lost Lake warm enough to swim?
At its typical summer peak of about 74°F, Lost Lake rates as "comfortable" for swimming. Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Where does this Lost 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 — 51 readings from 1 monitoring station between 2011 and 2024. 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.