St. Croix Lake Water Temperature
St. Croix Lake in Washington County, Minnesota averages about 75°F at the surface in summer — warmest in Jul (~75°F) and coldest in Sep (~71°F). These are typical values by month, not a live reading.
Typical water temperature by month
Typical surface water temperature by month, from 22 field readings (2023–2023) via the EPA Water Quality Portal. Months with too few readings are left blank.
Is St. Croix Lake warm enough to swim?
Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Want more than temperature? St. Croix Lake scored C on water quality — clarity, algae, phosphorus, depth, fish species, and swimming safety, all on one report card.
Water temperatures at nearby Minnesota lakes
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Frequently asked questions
What is the water temperature of St. Croix Lake?
St. Croix Lake has a typical summer surface temperature of about 75°F. It is usually warmest in July (around 75°F) and coldest in September (around 71°F). These are typical values by month from 22 EPA Water Quality Portal field readings (2023–2023), not a live reading.
When is St. Croix Lake warmest?
Surface water at St. Croix Lake is typically warmest in July, reaching about 75°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 St. Croix Lake warm enough to swim?
At its typical summer peak of about 75°F, St. Croix Lake rates as "comfortable" for swimming. Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Where does this St. Croix 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 — 22 readings from 1 monitoring station between 2023 and 2023. 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.