Harmony Lake Water Temperature
Harmony Lake in Mercer County, North Dakota averages about 61°F at the surface in summer — warmest in Jun (~66°F) and coldest in Oct (~49°F). These are typical values by month, not a live reading.
Typical water temperature by month
Typical surface water temperature by month, from 18 field readings (2023–2023) via the EPA Water Quality Portal. Months with too few readings are left blank.
Is Harmony Lake warm enough to swim?
Brisk but swimmable for short dips — most people acclimate after the first few minutes.
Want more than temperature? Harmony Lake scored C on water quality — clarity, algae, phosphorus, depth, fish species, and swimming safety, all on one report card.
Water temperatures at nearby North Dakota lakes
Summer average ~66°F
Summer average ~79°F
Summer average ~64°F
Summer average ~67°F
Summer average ~63°F
Summer average ~60°F
Explore water temperatures
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Frequently asked questions
What is the water temperature of Harmony Lake?
Harmony Lake has a typical summer surface temperature of about 61°F. It is usually warmest in June (around 66°F) and coldest in October (around 49°F). These are typical values by month from 18 EPA Water Quality Portal field readings (2023–2023), not a live reading.
When is Harmony Lake warmest?
Surface water at Harmony Lake is typically warmest in June, reaching about 66°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 Harmony Lake warm enough to swim?
At its typical summer peak of about 61°F, Harmony Lake rates as "cool" for swimming. Brisk but swimmable for short dips — most people acclimate after the first few minutes.
Where does this Harmony 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 — 18 readings from 2 monitoring stations 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.