Lake Ontario Sets Record Warm Surface Temperatures

Surface water averaged about 56.3°F on November 8, a new record for the day and nearly 6°F above the long-term average.

Updated on Nov. 9, 2026 in Severe Weather

Open dark blue-grey lake water meets a pale gravel shoreline, with thin vapor rising from the water under overcast late-autumn light and bare trees in the distance. — Lake Ontario's average surface temperature reached about 56.3°F on November 8, a daily record nearly 6°F above the long-term average. AI Illustration. Upload story photo >

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Lake Ontario's average surface temperature reached about 56.3°F as of November 8, a new daily record. Daily record-high surface temperatures have been recorded since November 3.

Why it matters

Warmer lake water means cold air needs to be less frigid to trigger lake-effect snow, and a larger temperature difference can produce more intense lake-effect bands. The warm water could affect the type and amount of precipitation expected in the Rochester area this weekend.

The GLSEA surface temperature record shows Lake Ontario averaging about 56.3°F on November 8, compared with a 1995–2025 average of about 50.6°F for this time of year. Forecasters have not said how much this warmth will change expected precipitation totals this weekend.

The details

Lake Ontario surface water temperatures are tracked by the Great Lakes Surface Environmental Analysis, which has kept records since 1995. Lake-effect snow forms when cold air moves over a warm body of water, and a blast of cold air from Canada could coincide with moisture moving through the northeastern United States at the end of the week.

November 3: Daily record-high surface temperatures began on Lake Ontario.
November 5, 2024: Rochester's air temperature hit a record 81°F.
November 8: Lake Ontario's average surface temperature reached a record 56.3°F.
Friday through Saturday: Cold air and moisture could bring lake-effect precipitation.

Seasonal Patterns

Lake Ontario's November 8 reading of 56.3°F sits about 1.5°F above the previous record, extending a GLSEA dataset that has been recorded since 1995. The warmth comes as the lake runs nearly 6°F above its 1995–2025 average for this time of year.

Residents near Lake Ontario, including Rochester, should monitor forecasts for lake-effect precipitation Friday and Saturday as cold air moves in. Travelers in the affected corridor should allow extra time for possible snow-related driving conditions.

The takeaway

Warm lake water can make cold-air outbreaks more likely to produce heavy lake-effect bands, so the reading is worth tracking this week. Residents should watch the forecast for changes in the weekend's precipitation type and amount.