Lake Michigan Water Level History & Climatology
Station: Lake Michigan at Milwaukee, WI (NOAA_COOPS 9087031) • Datum: IGLD85
How to Read Historical Percentiles
At the 62th percentile, this level is typical for the date and falls within the middle 50% of the 164 years on record.
A reading in the middle 50% band (25th to 75th percentile) represents typical seasonal operating levels. Levels below the 25th percentile signify drought conditions or heavy fall drawdowns, while levels above the 75th percentile occur after unusually wet weather or flood-storage impoundment.
Monthly Elevation Climatology Table
Calculated across all 164 years of verified daily records for Lake Michigan.
| Month | 10th %ile (Low) | 25th %ile (Lower) | Median (Typical) | 75th %ile (Upper) | 90th %ile (High) | Record Range |
|---|---|---|---|---|---|---|
| January | 577.66 | 578.05 | 578.47 | 578.89 | 579.28 | 577.0 – 579.7 |
| February | 577.92 | 578.31 | 578.73 | 579.15 | 579.54 | 577.2 – 580.0 |
| March | 578.30 | 578.69 | 579.11 | 579.53 | 579.92 | 577.5 – 580.4 |
| April | 578.71 | 579.10 | 579.52 | 579.94 | 580.33 | 577.9 – 580.8 |
| May | 579.03 | 579.42 | 579.84 | 580.26 | 580.65 | 578.3 – 581.1 |
| June | 579.18 | 579.57 | 579.99 | 580.41 | 580.80 | 578.6 – 581.1 |
| July | 579.11 | 579.50 | 579.92 | 580.34 | 580.73 | 578.4 – 581.1 |
| August | 578.84 | 579.23 | 579.65 | 580.07 | 580.46 | 578.1 – 580.9 |
| September | 578.45 | 578.84 | 579.26 | 579.68 | 580.07 | 577.7 – 580.6 |
| October Current | 578.04 | 578.43 | 578.85 | 579.27 | 579.66 | 577.3 – 580.2 |
| November | 577.72 | 578.11 | 578.53 | 578.95 | 579.34 | 577.0 – 579.8 |
| December | 577.58 | 577.97 | 578.39 | 578.81 | 579.20 | 577.0 – 579.6 |
Hydrology & Property Risk Context
Dock & Boat Slip Usability
Floating docks need enough water under their pivots and gangways during seasonal fall drawdowns. Fixed docks face grounding if lake elevation drops below the piling footings.
Calculate Slip Clearance →Seasonal Operating Rule Curves
Reservoirs managed by the U.S. Army Corps of Engineers or local river authorities intentionally lower pool targets in autumn to capture heavy winter and spring runoff.
View Seasonal Guide Curve →Waterfront Property Buyers
Never buy a lake home based only on the water line you see on a single weekend. Check multi-decade low-water extremes to ensure your cove does not turn into dry mud during multi-year droughts.
Generate Elevation Risk Report →