Riley Lake Water Temperature
Riley Lake in Hennepin County, Minnesota averages about 62°F at the surface in summer — warmest in Jul (~63°F) and coldest in Jan (~37°F). These are typical values by month, not a live reading.
Typical water temperature by month
Typical surface water temperature by month, from 1,474 field readings (2010–2025) via the EPA Water Quality Portal. Months with too few readings are left blank.
Is Riley Lake warm enough to swim?
Brisk but swimmable for short dips — most people acclimate after the first few minutes.
Want more than temperature? Riley Lake scored B 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 Riley Lake?
Riley Lake has a typical summer surface temperature of about 62°F. It is usually warmest in July (around 63°F) and coldest in January (around 37°F). These are typical values by month from 1,474 EPA Water Quality Portal field readings (2010–2025), not a live reading.
When is Riley Lake warmest?
Surface water at Riley Lake is typically warmest in July, reaching about 63°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 Riley Lake warm enough to swim?
At its typical summer peak of about 62°F, Riley Lake rates as "cool" for swimming. Brisk but swimmable for short dips — most people acclimate after the first few minutes.
Where does this Riley 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 — 1,474 readings from 2 monitoring stations between 2010 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.