Joe Martin Lake Water Temperature
Joe Martin Lake in St. Louis County, Minnesota averages about 65°F at the surface in summer — warmest in Jul (~76°F) and coldest in May (~47°F). These are typical values by month, not a live reading.
Typical water temperature by month
Typical surface water temperature by month, from 479 field readings (2010–2021) via the EPA Water Quality Portal. Months with too few readings are left blank.
Is Joe Martin Lake warm enough to swim?
Brisk but swimmable for short dips — most people acclimate after the first few minutes.
Want more than temperature? Joe Martin 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 Joe Martin Lake?
Joe Martin Lake has a typical summer surface temperature of about 65°F. It is usually warmest in July (around 76°F) and coldest in May (around 47°F). These are typical values by month from 479 EPA Water Quality Portal field readings (2010–2021), not a live reading.
When is Joe Martin Lake warmest?
Surface water at Joe Martin Lake is typically warmest in July, reaching about 76°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 Joe Martin Lake warm enough to swim?
At its typical summer peak of about 65°F, Joe Martin Lake rates as "cool" for swimming. Brisk but swimmable for short dips — most people acclimate after the first few minutes.
Where does this Joe Martin 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 — 479 readings from 2 monitoring stations between 2010 and 2021. 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.