Grays Lake Water Temperature
Grays Lake in Polk County, Iowa typically sits around 73°F at the surface in September — warmest in Jul (~82°F) and coldest in Sep (~73°F). That is a typical value for the month, not a live reading.
Typical water temperature by month
Typical surface water temperature by month, from 16 field readings (2018–2026) via the EPA Water Quality Portal. Months with too few readings are left blank.
Is Grays Lake warm enough to swim?
Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Want more than temperature? Grays Lake scored F on water quality — clarity, algae, phosphorus, depth, fish species, and swimming safety, all on one report card.
Water temperatures at nearby Iowa lakes
Summer average ~79°F
Summer average ~77°F
Summer average ~86°F
Summer average ~78°F
Summer average ~77°F
Summer average ~80°F
Explore water temperatures
Where to stay near Grays Lake
Planning a swim or lake trip? Compare cabins, lodges, and vacation rentals near Grays 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 Grays Lake
Prices for Sep 4–6, 4 adults. Change dates on the map below.
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Frequently asked questions
What is the water temperature of Grays Lake?
Grays Lake typically sits around 73°F at the surface in September, from 16 EPA Water Quality Portal field readings (2018–2026). That is a typical value for the month, not a live reading.
When is Grays Lake warmest?
Surface water at Grays Lake is typically warmest in July, reaching about 82°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 Grays Lake warm enough to swim?
At its typical summer peak of about 79°F, Grays Lake rates as "comfortable" for swimming. Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Where does this Grays 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 — 16 readings from 2 monitoring stations between 2018 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.