Grass Lake Water Temperature
Grass Lake in Shawano County, Wisconsin averages about 80°F at the surface in summer — warmest in Jul (~80°F) and coldest in Apr (~54°F). These are typical values by month, not a live reading.
Typical water temperature by month
Typical surface water temperature by month, from 11 field readings (2024–2026) via the EPA Water Quality Portal. Months with too few readings are left blank.
Is Grass Lake warm enough to swim?
Very comfortable for swimming. Warm surface water can also favor blue-green algae in nutrient-rich lakes, so check for advisories before you go in.
Want more than temperature? Grass Lake scored B 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 Grass Lake?
Grass Lake has a typical summer surface temperature of about 80°F. It is usually warmest in July (around 80°F) and coldest in April (around 54°F). These are typical values by month from 11 EPA Water Quality Portal field readings (2024–2026), not a live reading.
When is Grass Lake warmest?
Surface water at Grass Lake is typically warmest in July, reaching about 80°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 Grass Lake warm enough to swim?
At its typical summer peak of about 80°F, Grass Lake rates as "warm" for swimming. Very comfortable for swimming. Warm surface water can also favor blue-green algae in nutrient-rich lakes, so check for advisories before you go in.
Where does this Grass 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 — 11 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.