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LakeQuality
A wave breaking on the cobble beach of Lake Superior at Duluth, Minnesota, with a wooded headland beyond

Isabella Lake Water Temperature

Isabella Lake in Lake County, Minnesota typically sits around 44°F at the surface in October — warmest in Jul (~71°F) and coldest in Oct (~44°F). That is a typical value for the month, not a live reading.

Typical in October
44°F
Very cold
Summer average
68°F
Warmest (Jul)
71°F
Coldest (Oct)
44°F

Typical water temperature by month

Jan
Feb
Mar
Apr
59°
May
64°
Jun
71°
Jul
70°
Aug
58°
Sep
44°
Oct
Nov
Dec

Column height runs from this lake’s coldest month (44°F) to its warmest (71°F).

Typical surface water temperature by month, from 65 field readings (2011–2025) via the EPA Water Quality Portal. Months with too few readings are left blank.

Is Isabella Lake warm enough to swim?

At its summer peak (~68°F): Cool

Brisk but swimmable for short dips — most people acclimate after the first few minutes.

Want more than temperature? Isabella Lake water quality: clarity, algae, phosphorus, depth, fish species, and current advisories, all on one page.

Where to stay near Isabella Lake

Planning a swim or lake trip? Compare cabins, lodges, and vacation rentals near Isabella 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 Isabella Lake

Prices for Oct 23–25, 4 adults. Change dates on the map below.

Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.

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Frequently asked questions

What is the water temperature of Isabella Lake?

Isabella Lake typically sits around 44°F at the surface in October, from 65 EPA Water Quality Portal field readings (2011–2025). That is a typical value for the month, not a live reading.

When is Isabella Lake warmest?

Surface water at Isabella Lake is typically warmest in July, reaching about 71°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 Isabella Lake warm enough to swim?

At its typical summer peak of about 68°F, Isabella Lake rates as "cool" for swimming. Brisk but swimmable for short dips — most people acclimate after the first few minutes.

Where does this Isabella 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 — 65 readings from 1 monitoring station between 2011 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.