Find the newest coordinated Great Lakes monthly outlook first, followed by earlier baselines. Reports compare official lake-wide means with the prior month, prior year, long-term averages, and the joint USACE/Environment and Climate Change Canada six-month forecast. Recent values are preliminary or provisional and referenced to IGLD 1985. Current U.S. references use Lake America (Lake Ontario), while official source tables and international material may retain Lake Ontario.
Latest monthly outlook
Great Lakes Water Levels Monthly Outlook: September 2026
The September outlook presents the coordinated August monthly means, comparisons with July, August 2025, and long-term August averages, plus the official September 2026–February 2027 forecast and practical shoreline guidance.
Earlier monthly baseline
August baseline
| Lake system | Aug. 17 daily mean | Feet | Direction since Aug. 10 |
|---|---|---|---|
| Lake Superior | 183.51 m | 602.07 ft | Level |
| Michigan–Huron | 176.60 m | 579.40 ft | Down 2 cm |
| Lake St. Clair | 175.36 m | 575.33 ft | Up 2 cm |
| Lake Erie | 174.42 m | 572.24 ft | Level |
| Lake America (Lake Ontario) | 75.27 m | 246.95 ft | Down 5 cm |
How the monthly outlook works
The coordinated Great Lakes outlook combines observed water levels with seasonal projections developed by U.S. and Canadian agencies. The next full report will compare the official monthly mean with the previous month, the same month last year, the long-term average, and the coordinated six-month forecast. We will not substitute a partial-month daily value for an official monthly mean.
Practical interpretation
Lake-wide means help identify broad seasonal direction, but they do not show the depth at a specific dock or channel. Boaters should continue using current charts, local gauges, weather forecasts, and on-site depth information. Shoreline flooding and erosion risk also depend heavily on wind, waves, storm tracks, ice conditions, and local geography.
Official sources
- NOAA GLERL water levels and seasonal forecasts
- NOAA GLERL long-term dashboard
- USACE Great Lakes Daily Water Levels
Current Great Lakes levels · Weekly updates