09/30/2025
Great Lakes Climatology, Meteorology & Natural-Hazard Risks
1) Regional climate snapshot
The setting: The Great Lakes (Superior, Michigan, Huron, Erie, Ontario) hold ~20% of the world’s fresh surface water. Their sheer size modifies nearby weather year-round. NOAA’s Great Lakes lab (GLERL) maintains long records of lake temperature, ice, and storms that show strong lake–atmosphere coupling.
glerl.noaa.gov
A warming/icing trend: Winters over the lakes are getting shorter by ~two weeks since the mid-1990s, and recent winters have featured very low ice cover, which favors larger open-water heat and moisture fluxes.
research.noaa.gov
+1
2) How the lakes shape weather
Lake-effect snow (LES): Cold air moving over much milder, open water picks up heat and moisture, building narrow snow bands downwind. Slight wind shifts move bands dramatically, creating huge local differences over a few miles. Low-ice winters amplify LES; once lakes freeze, LES wanes.
Climate.gov
Lake breezes & temperature moderation: In warm seasons, onshore breezes cool immediate shorelines by day and can trigger showers/storms where lake and land air masses collide; in winter, lakes slightly warm nearby coasts, trimming the harshest overnight lows (until they freeze).
Cloud/precip enhancement: Long fetches can enhance rain or snow in synoptic storms (lake-enhanced events), not just pure LES.
Fog: Warm, humid air over colder lake water (or vice-versa) promotes advection fog and sea smoke.
Waterspouts: Late summer–early fall, steep lapse rates over warm lakes support non-supercell waterspouts.
Seiches & coastal hazards: Pressure jumps or wind shifts can slosh water across a lake, rapidly raising/lowering levels. A notorious Lake Michigan seiche on June 26, 1954 produced a ~10-ft surge in Chicago, killing eight.
encyclopedia.chicagohistory.org
3) Biggest natural-disaster risks in the Great Lakes states
(MN, WI, IL, IN, MI, OH, PA, NY; relative importance varies by state and by proximity to the lakes.)
Severe convective storms (damaging winds/derechos, hail, tornadoes): These are the most frequent, high-loss events in the region’s disaster statistics. NOAA’s “Billion-Dollar Disasters” tallies show severe storms dominate losses for many Great Lakes states (e.g., Michigan: 41 severe-storm disasters since 1980).
NCEI
+1
Winter storms (blizzards, ice storms, extreme LES): Recurrent, occasionally crippling, especially downwind of Erie/Ontario and across the Upper Peninsula/north woods.
NCEI
Flooding (flash, riverine, and coastal/lakeshore): Stationary warm-season thunderstorms can dump exceptional rain (see the 2019 Michigan record below). High-water periods plus storms drive erosion and lakeshore flooding.
National Weather Service
Heat waves/cold snaps: Still impactful—classic records cluster in the 1930s (heat) and mid-20th century (cold), though heat risk is rising with urbanization and climate warming.
National Weather Service
Seiches & wave/surge events: Less frequent than 1–3 but locally dangerous; they strike fast with little warning.
encyclopedia.chicagohistory.org
Bottom line on risk: For planning and infrastructure, the most consequential recurring hazards are (a) severe thunderstorms and (b) winter storms/LES, with (c) flooding/coastal hazards close behind. State-by-state loss histories back this up.
NCEI
+1
4) Notable extreme weather records (examples)
(Authoritative, vettable records; you can swap in other states if you prefer.)
Michigan (state-certified extremes, plus a LES exemplar just across the border):
Hottest temperature: 112°F at Mio, July 13, 1936.
Stacker
Coldest temperature: −51°F at Vanderbilt, Feb 9, 1934.
NCEI
24-hour rainfall (state record): 12.92 inches near Fountain/Branch Twp (Mason Co.), July 20, 2019 — validated by NOAA’s State Climate Extremes Committee, with NWS event docs.
NCEI
+1
Lake-effect snow benchmark (NY, downwind of Lake Erie): 81.2 inches Nov 17–20, 2022 (near Hamburg/Orchard Park, south of Buffalo). This is an excellent illustration of LES potential for Great Lakes lee shores.
National Weather Service
+1
5) Why low ice matters for your future winters
Recent winters with exceptionally low ice cover (e.g., ~7% mid-Feb 2023; very low again in 2024) allow more lake heat/moisture flux, tending to increase the potential for intense LES early/mid-winter even as average winters warm. Expect bigger swings: rain-to-snow events, lake-enhanced blizzards, and rapid-freeze hazards when arctic fronts blast through.
glerl.noaa.gov
+1
Quick primer: how lake-effect snow forms (one paragraph you can quote)
Cold, dry air traverses warm, open lake water and picks up heat and v***r. Turbulent mixing creates convective rolls that organize into narrow snow bands aligned with the wind fetch. Where a band stalls, snowfall rates can exceed 3–5 inches/hour and totals can reach feet in a day or two, while areas a few miles away see little. Band placement is extremely sensitive to wind direction and shoreline topography; ice cover largely shuts it down.
Climate.gov
6) Planning takeaways for Great Lakes states
Design for wind & ice: Harden power and communications for damaging straight-line winds/icing—your most common high-loss triggers.
NCEI
Stormwater capacity matters: The region experiences short-duration deluges capable of >10" in 24 hours; size culverts and detention accordingly.
National Weather Service
Lakeshore management: Track water-level cycles and seiche risks; use setback/armoring where appropriate and improve rapid warning for harbor surges.
encyclopedia.chicagohistory.org
LES logistics: Pre-stage plows/salt and band-aware staffing for corridor-specific closures (Erie snowbelts, Tug Hill, U.P., leeward Lake Michigan).
National Weather Service
Monitor ice trends: Low-ice winters are becoming more common—expect higher early-season LES potential and more winter rain/flash-freeze hazards
