Mark Twain Lake Water Temperature
Mark Twain Lake in Ralls County, Missouri averages about 79°F at the surface in summer — warmest in Jul (~82°F) and coldest in Apr (~54°F). These are typical values by month, not a live reading.
Typical water temperature by month
Typical surface water temperature by month, from 106 field readings (2010–2020) via the EPA Water Quality Portal. Months with too few readings are left blank.
Is Mark Twain Lake warm enough to swim?
Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Want more than temperature? Mark Twain Lake scored D on water quality — clarity, algae, phosphorus, depth, fish species, and swimming safety, all on one report card.
Water temperatures at nearby Missouri lakes
Summer average ~78°F
Summer average ~83°F
Summer average ~77°F
Summer average ~81°F
Summer average ~82°F
Summer average ~82°F
Explore water temperatures
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Frequently asked questions
What is the water temperature of Mark Twain Lake?
Mark Twain Lake has a typical summer surface temperature of about 79°F. It is usually warmest in July (around 82°F) and coldest in April (around 54°F). These are typical values by month from 106 EPA Water Quality Portal field readings (2010–2020), not a live reading.
When is Mark Twain Lake warmest?
Surface water at Mark Twain 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 Mark Twain Lake warm enough to swim?
At its typical summer peak of about 79°F, Mark Twain Lake rates as "comfortable" for swimming. Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Where does this Mark Twain 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 — 106 readings from 1 monitoring station between 2010 and 2020. 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.