Lake Poygan Water Temperature
Lake Poygan in Winnebago County, Wisconsin averages about 75°F at the surface in summer — warmest in Jul (~76°F) and coldest in Oct (~52°F). These are typical values by month, not a live reading.
Typical water temperature by month
Typical surface water temperature by month, from 46 field readings (2024–2026) via the EPA Water Quality Portal. Months with too few readings are left blank.
Is Lake Poygan warm enough to swim?
Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Want more than temperature? Lake Poygan scored F on water quality — clarity, algae, phosphorus, depth, fish species, and swimming safety, all on one report card.
Water temperatures at nearby Wisconsin lakes
Summer average ~75°F
Summer average ~75°F
Summer average ~77°F
Summer average ~77°F
Summer average ~78°F
Summer average ~78°F
Explore water temperatures
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Frequently asked questions
What is the water temperature of Lake Poygan?
Lake Poygan has a typical summer surface temperature of about 75°F. It is usually warmest in July (around 76°F) and coldest in October (around 52°F). These are typical values by month from 46 EPA Water Quality Portal field readings (2024–2026), not a live reading.
When is Lake Poygan warmest?
Surface water at Lake Poygan 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 Lake Poygan warm enough to swim?
At its typical summer peak of about 75°F, Lake Poygan rates as "comfortable" for swimming. Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Where does this Lake Poygan 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 — 46 readings from 1 monitoring station between 2024 and 2026. 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.