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Do Lakes Have Tides? What the Great Lakes Actually Experience

Technically, yes — any body of water on Earth is pulled on by the moon and sun. In practice, lake tides are so small you'd never notice them, and something else is usually behind the water-level swings people actually see.

Why lake tides are basically invisible

The tidal bulge that creates ocean tides comes from the difference in gravitational pull across a large body of water — the near side pulled slightly more than the far side. A lake, even a large one, is too small for that difference to matter much. NOAA has measured a genuine tide on the Great Lakes, but it amounts to roughly an inch or two of vertical range, compared to feet or tens of feet on the open ocean.

So what's actually causing the water to rise and fall?

What people notice on the Great Lakes is almost always a seiche — a standing wave that sloshes back and forth across a lake basin, caused by strong wind or a sudden change in atmospheric pressure pushing water toward one shore. Seiches can raise water levels by several feet in a matter of hours on a lake like Erie, which is shallow and long enough to be especially prone to them — dwarfing the actual tidal signal entirely.

Seasonal and long-term changes are a separate thing again

The Great Lakes also see water levels shift over weeks and years due to precipitation, snowmelt, and evaporation — a slow cycle that has nothing to do with tides or seiches. NOAA and the Army Corps of Engineers track this separately from the short-term water level data.

The takeaway

If you're on a lake and the water noticeably rose or fell over a few hours, you were watching wind and pressure at work, not the moon. True tide charts and predictions, like the ones Simple Tides shows, are really an ocean and coastal-water story — see our guide to NOAA stations for how those predictions are built.