Lk Ontario Lake Water Temperature
Lk Ontario Lake in Monroe County, New York averages about 72°F at the surface in summer — warmest in Jul (~77°F) and coldest in Apr (~41°F). These are typical values by month, not a live reading.
Typical water temperature by month
Typical surface water temperature by month, from 28 field readings (2018–2023) via the EPA Water Quality Portal. Months with too few readings are left blank.
Is Lk Ontario Lake warm enough to swim?
Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Want more than temperature? Lk Ontario Lake scored D on water quality — clarity, algae, phosphorus, depth, fish species, and swimming safety, all on one report card.
Water temperatures at nearby New York lakes
Summer average ~76°F
Summer average ~74°F
Summer average ~73°F
Summer average ~73°F
Summer average ~75°F
Summer average ~74°F
Explore water temperatures
Where to stay near Lk Ontario Lake
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Frequently asked questions
What is the water temperature of Lk Ontario Lake?
Lk Ontario Lake has a typical summer surface temperature of about 72°F. It is usually warmest in July (around 77°F) and coldest in April (around 41°F). These are typical values by month from 28 EPA Water Quality Portal field readings (2018–2023), not a live reading.
When is Lk Ontario Lake warmest?
Surface water at Lk Ontario Lake is typically warmest in July, reaching about 77°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 Lk Ontario Lake warm enough to swim?
At its typical summer peak of about 72°F, Lk Ontario Lake rates as "comfortable" for swimming. Pleasant for swimming — the range most people find enjoyable without a wetsuit.
Where does this Lk Ontario 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 — 28 readings from 2 monitoring stations between 2018 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.