Lily Lake Water Temperature
Lily Lake in McHenry County, Illinois averages about 73°F at the surface in summer — warmest in Aug (~76°F) and coldest in Oct (~58°F). These are typical values by month, not a live reading.
Typical water temperature by month
Typical surface water temperature by month, from 160 field readings (2012–2021) via the EPA Water Quality Portal. Months with too few readings are left blank.
Is Lily Lake warm enough to swim?
Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Want more than temperature? Lily 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 Lily Lake?
Lily Lake has a typical summer surface temperature of about 73°F. It is usually warmest in August (around 76°F) and coldest in October (around 58°F). These are typical values by month from 160 EPA Water Quality Portal field readings (2012–2021), not a live reading.
When is Lily Lake warmest?
Surface water at Lily Lake is typically warmest in August, 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 Lily Lake warm enough to swim?
At its typical summer peak of about 73°F, Lily Lake rates as "comfortable" for swimming. Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Where does this Lily 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 — 160 readings from 3 monitoring stations between 2012 and 2021. 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.