Rainbow Lake Water Temperature
Rainbow Lake in Vilas County, Wisconsin averages about 69°F at the surface in summer — warmest in Jul (~72°F) and coldest in Apr (~47°F). These are typical values by month, not a live reading.
Typical water temperature by month
Typical surface water temperature by month, from 10 field readings (2024–2025) via the EPA Water Quality Portal. Months with too few readings are left blank.
Is Rainbow Lake warm enough to swim?
Brisk but swimmable for short dips — most people acclimate after the first few minutes.
Want more than temperature? Rainbow Lake scored B 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 ~71°F
Summer average ~72°F
Summer average ~72°F
Summer average ~73°F
Summer average ~74°F
Summer average ~73°F
Explore water temperatures
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Frequently asked questions
What is the water temperature of Rainbow Lake?
Rainbow Lake has a typical summer surface temperature of about 69°F. It is usually warmest in July (around 72°F) and coldest in April (around 47°F). These are typical values by month from 10 EPA Water Quality Portal field readings (2024–2025), not a live reading.
When is Rainbow Lake warmest?
Surface water at Rainbow Lake is typically warmest in July, reaching about 72°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 Rainbow Lake warm enough to swim?
At its typical summer peak of about 69°F, Rainbow Lake rates as "cool" for swimming. Brisk but swimmable for short dips — most people acclimate after the first few minutes.
Where does this Rainbow 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 — 10 readings from 1 monitoring station between 2024 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.