Rays Lake Water Temperature
Rays Lake in Le Sueur County, Minnesota averages about 68°F at the surface in summer — warmest in Jul (~69°F) and coldest in May (~61°F). These are typical values by month, not a live reading.
Typical water temperature by month
Typical surface water temperature by month, from 245 field readings (2017–2025) via the EPA Water Quality Portal. Months with too few readings are left blank.
Is Rays Lake warm enough to swim?
Brisk but swimmable for short dips — most people acclimate after the first few minutes.
Want more than temperature? Rays Lake scored D 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 ~57°F
Summer average ~81°F
Summer average ~73°F
Summer average ~78°F
Summer average ~63°F
Summer average ~59°F
Explore water temperatures
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Frequently asked questions
What is the water temperature of Rays Lake?
Rays Lake has a typical summer surface temperature of about 68°F. It is usually warmest in July (around 69°F) and coldest in May (around 61°F). These are typical values by month from 245 EPA Water Quality Portal field readings (2017–2025), not a live reading.
When is Rays Lake warmest?
Surface water at Rays Lake is typically warmest in July, reaching about 69°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 Rays Lake warm enough to swim?
At its typical summer peak of about 68°F, Rays Lake rates as "cool" for swimming. Brisk but swimmable for short dips — most people acclimate after the first few minutes.
Where does this Rays 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 — 245 readings from 1 monitoring station between 2017 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.