Oswego Lake Effect Snow

Q: How much snow does Oswego get in a year?

140.1 inches per season, per NOAA NCEI's official 1991-2020 climate normals for OSWEGO, NY US. Lake effect gradients are extreme, so nearby towns can run far higher or lower than this single station.

Q: When is lake effect snow season in Oswego?

The months with a NOAA normal of at least 1 inch at OSWEGO, NY US run November through April, peaking in January at 44.7 inches. The lake effect core is November through February: it starts when arctic air first crosses the still-warm lake and winds down as the water cools.

Q: Where do these snowfall numbers come from?

From NOAA NCEI's 1991-2020 U.S. Climate Normals for OSWEGO, NY US, station USC00306314, read from NCEI's public data service. They are 30 year averages, not a forecast for this winter: individual lake effect seasons swing enormously around the normal.

Why Lake Ontario buries Oswego, what NOAA's 1991-2020 normals show, and every active NWS winter product, as issued.

Season normal: 140.1 inches at OSWEGO, NY US

Seasonal snowfall normal

140 in

Snowiest month

January

The lake

Lake Ontario

Oswego snowfall, by the numbers

NOAA NCEI normals, 1991-2020

140.1 in

seasonal normal

OSWEGO, NY US

44.7 in

in January alone

the peak month

Nov to Apr

months with 1 in or more

the season window

Lake Ontario

the engine

NY snowbelt

Every figure is NOAA NCEI’s official 1991-2020 climate normal for the named station, OSWEGO, NY US (USC00306314). Lake effect gradients are sharp: a few miles can change a season total by feet.

The calendar

Month by month snowfall in Oswego

NOAA’s 1991-2020 monthly snowfall normals for OSWEGO, NY US, laid out as a snow season from July to June. Lake effect climates load their totals into the cold months when the lake is still open water; watch how fast the bars rise in November and fall off late winter.

Jul

Aug

Sep

Oct

Nov

Dec

Jan

Feb

Mar

Apr

May

Jun

Monthly snowfall normals (inches), OSWEGO, NY US, NOAA NCEI 1991-2020 U.S. Climate Normals.

Satellite view of parallel lake effect snow bands streaming southeast off all five Great Lakes — Lake effect snow bands streaming off the Great Lakes, in a NOAA satellite view. Cold air crossing warm water organizes into these parallel cloud streets, and where one comes ashore it snows hard while the next town over sees sun. “Lake effect snow bands over the Great Lakes region” — NOAA — Public domain

The mechanism

Why Oswego gets lake effect snow

Oswego sits directly on Lake Ontario's southeastern shore, first landfall for bands that form along the lake's nearly 200 mile long axis on a westerly wind. The same geometry that occasionally buries the city in multi-foot single-band events also feeds the Tug Hill Plateau just inland, and Oswego County place names fill the top of nearly every New York lake effect storm report.

The physics, in the National Weather Service’s own words: “Lake Effect snow occurs when cold air, often originating from Canada, moves across the open waters of the Great Lakes... The air rises, clouds form and grow into narrow band that produces 2 to 3 inches of snow per hour or more.” And on location: “Wind direction is a key component in determining which areas will receive lake effect snow. Heavy snow may be falling in one location, while the sun may be shining just a mile or two away in either direction.” (NWS, What is Lake Effect Snow?)

Satellite view of snow covered snowbelts downwind of Lake Erie and Lake Ontario with both lakes open — Lake Erie, Lake Ontario and their snowbelts from NASA's MODIS, January 13, 2017. The white land downwind of each lake is the belt itself: snow drawn on the map by fetch and wind direction. “Lake Erie, Lake Ontario, and the Finger Lakes” — Jeff Schmaltz, MODIS Land Rapid Response Team, NASA GSFC — Public domain

Live, as issued

Winter weather products covering NY right now

Every active National Weather Service winter product for New York, read live from api.weather.gov and reproduced exactly as issued. Zones are larger than the city, so confirm the listed areas include yours.

Checking api.weather.gov for active winter weather products…

Why the mixed product names: for the 2017-2018 winter the NWS consolidated its lake effect products into the general winter suite. The Lake Effect Snow Warning came back on October 1, 2019, but per Service Change Notice 19-63 its use is “optional at Regional discretion” and offices may still issue Winter Storm Warnings “with the lake effect component specified in the ‘What’ section”. The old Lake Effect Snow Watch and Advisory were never reinstated. So this page passes through every winter product for the area and tags the ones whose own NWS text names lake effect.

Whiteout and travel decisions belong with the National Weather Service (weather.gov winter safety) and the New York 511 system (511 road conditions). NWS products above are reproduced as issued.

The season

When lake effect season runs, and what ends it

Lake effect season opens with the first arctic outbreaks over still-warm water, usually November, and the early-season events are often the most violent because the lake is warmest. What closes the season depends on the lake: shallow Lake Erie usually freezes and shuts its machine off, while deep Lake Ontario and Lake Superior stay mostly open and can produce all winter.

Lake Erie

80%

average annual maximum ice cover; 34 of 53 winters peaked at 90% or more. The shallowest Great Lake freezes, and its snow machine stops.

Lake Ontario

29%

average annual maximum ice cover; only 7 of 53 winters even reached 50%. The deep lake stays open, and its belt keeps running.

Our averages, computed from NOAA GLERL’s daily Great Lakes ice cover record (GLICD), ice years 1973 to 2025: for each winter we take the season’s peak daily lake-averaged ice cover, then average those peaks.

A dark wall of lake effect snow advancing across Lake Erie toward the Buffalo waterfront — The wall of snow: the leading edge of the November 2014 lake effect band advancing on Buffalo, from the NOAA Photo Library. NWS Buffalo wrote that the band edge was so sharp "many described it as a wall of snow"; every Great Lakes belt town knows a smaller version of this sky. “Snowfall descending on the Buffalo Southtowns” — NOAA Photo Library, NWS Collection — Public domain

Common questions

Oswego lake effect snow FAQ

Why does Oswego get so much snow?

How much snow does Oswego get in a year?

When is lake effect snow season in Oswego?

Is there a lake effect snow warning in Oswego right now?

The live panel on this page lists every active NWS winter product for the state, straight from api.weather.gov: Lake Effect Snow Warning, Winter Storm Warning and Watch, Winter Weather Advisory, Blizzard Warning, and Snow Squall Warning. Since the NWS product consolidation, a lake effect event may be covered under a generic winter product name, so all of them are shown and the ones whose NWS text names lake effect are tagged.

What is lake effect snow?

In the NWS's words: "Lake Effect snow occurs when cold air, often originating from Canada, moves across the open waters of the Great Lakes. As the cold air passes over the unfrozen and relatively warm waters of the Great Lakes, warmth and moisture are transferred into the lowest portion of the atmosphere. The air rises, clouds form and grow into narrow band that produces 2 to 3 inches of snow per hour or more." For Oswego, the water in question is Lake Ontario.

Where do these snowfall numbers come from?

City of Buffalo boundary sign at night in wind driven lake effect snow — The city line at night during the November 2014 storm, photographed by Anthony Quintano. Inside a band, rates of 3 to 6 inches per hour with wind are what a Lake Effect Snow Warning is written for. “Historic Lake Effect Snow Hits Buffalo New York Area” by Anthony Quintano, CC BY 2.0

Elsewhere in the belts

Other snowbelt cities

New York lake effect snowThe statewide belt map this city sits inside, with records and the season shape.New York winter forecastNOAA's seasonal outlook for the whole winter, read for this state.Lake effect snow, nationwideEvery belt, the mechanism, and the Erie versus Ontario ice story.

Snowfall figures are NOAA NCEI 1991-2020 U.S. Climate Normals for OSWEGO, NY US (public domain), refreshed with each new normals release. Alerts read live from api.weather.gov and reproduced as issued. Ice statistics computed by us from NOAA GLERL daily records and labeled as our arithmetic. No safety advice of ours appears on this page.
Hero image: “Winter Storm Knife - Town Line, NY” by Anthony Quintano, CC BY 2.0