Lake South Water Temperature
Lake South in St. Johns County, Florida averages about 84°F at the surface in summer — warmest in Jul (~87°F) and coldest in Jan (~54°F). These are typical values by month, not a live reading.
Typical water temperature by month
Typical surface water temperature by month, from 20 field readings (2017–2024) via the EPA Water Quality Portal. Months with too few readings are left blank.
Is Lake South 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? Lake South scored D on water quality — clarity, algae, phosphorus, depth, fish species, and swimming safety, all on one report card.
Water temperatures at nearby Florida lakes
Summer average ~84°F
Summer average ~84°F
Summer average ~86°F
Summer average ~87°F
Summer average ~86°F
Summer average ~86°F
Explore water temperatures
Where to stay near Lake South
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Frequently asked questions
What is the water temperature of Lake South?
Lake South has a typical summer surface temperature of about 84°F. It is usually warmest in July (around 87°F) and coldest in January (around 54°F). These are typical values by month from 20 EPA Water Quality Portal field readings (2017–2024), not a live reading.
When is Lake South warmest?
Surface water at Lake South is typically warmest in July, reaching about 87°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 Lake South warm enough to swim?
At its typical summer peak of about 84°F, Lake South 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 Lake South 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 — 20 readings from 2 monitoring stations between 2017 and 2024. 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.