Onland Lake Water Temperature
Onland Lake in Portage County, Wisconsin typically sits around 65°F at the surface in October — warmest in Jul (~79°F) and coldest in Jan (~36°F). That is a typical value for the month, not a live reading.
Typical water temperature by month
Column height runs from this lake’s coldest month (36°F) to its warmest (79°F).
Typical surface water temperature by month, from 89 field readings (2024–2025) via the EPA Water Quality Portal. Months with too few readings are left blank.
Is Onland Lake warm enough to swim?
Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Want more than temperature? Onland Lake water quality: clarity, algae, phosphorus, depth, fish species, and current advisories, all on one page.
Water temperatures at nearby Wisconsin lakes
Summer average ~76°F
Summer average ~79°F
Summer average ~73°F
Summer average ~75°F
Summer average ~74°F
Summer average ~77°F
Explore water temperatures
Where to stay near Onland Lake
Planning a swim or lake trip? Compare cabins, lodges, and vacation rentals near Onland Lake — live availability and prices. Switch the map to Satellite to see the lake and how close each stay is to the water.
Top-rated places to stay near Onland Lake
Prices for Oct 23–25, 4 adults. Change dates on the map below.
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Frequently asked questions
What is the water temperature of Onland Lake?
Onland Lake typically sits around 65°F at the surface in October, from 89 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
When is Onland Lake warmest?
Surface water at Onland Lake is typically warmest in July, reaching about 79°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 Onland Lake warm enough to swim?
At its typical summer peak of about 77°F, Onland Lake rates as "comfortable" for swimming. Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Where does this Onland 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 — 89 readings from 1 monitoring station between 2024 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.