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

Sugar Lake Water Temperature

Sugar Lake in Cass County, Minnesota typically sits around 63°F at the surface in September — warmest in Aug (~68°F) and coldest in May (~57°F). That is a typical value for the month, not a live reading.

Typical in September
63°F
Cool
Summer average
66°F
Warmest (Aug)
68°F
Coldest (May)
57°F

Typical water temperature by month

Jan
Feb
Mar
Apr
May
57°
Jun
64°
Jul
67°
Aug
68°
Sep
63°
Oct
Nov
Dec

Typical surface water temperature by month, from 190 field readings (20162025) via the EPA Water Quality Portal. Months with too few readings are left blank.

Is Sugar Lake warm enough to swim?

At its summer peak (~66°F): Cool

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

Want more than temperature? Sugar Lake scored A on water quality — clarity, algae, phosphorus, depth, fish species, and swimming safety, all on one report card.

Where to stay near Sugar Lake

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

Prices for Sep 4–6, 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 Sugar Lake?

Sugar Lake typically sits around 63°F at the surface in September, from 190 EPA Water Quality Portal field readings (2016–2025). That is a typical value for the month, not a live reading.

When is Sugar Lake warmest?

Surface water at Sugar Lake is typically warmest in August, reaching about 68°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 Sugar Lake warm enough to swim?

At its typical summer peak of about 66°F, Sugar Lake rates as "cool" for swimming. Brisk but swimmable for short dips — most people acclimate after the first few minutes.

Where does this Sugar 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 — 190 readings from 1 monitoring station between 2016 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.