On January 4, 1998, an upper level low system stalled over the Great Lakes, pumping warm and moist air from the Gulf of Mexico toward the upper St. Lawrence Valley.
The upper flow then turned eastward, bringing this air mass down toward the Bay of Fundy.
At the same time, a high pressure center was sitting farther north in Labrador, keeping an easterly flow of very cold air near the surface.
An unusually strong Bermuda high pressure area was anchored over the Atlantic Ocean, which prevented these systems from moving further to the east, as most winter storms do when they pass over the Great Lakes–St.
Lawrence region.

A series of surface low pressure systems passed in this atmospheric circulation between January 5 and January 10, 1998.
For more than 80 hours, steady freezing rain and drizzle fell over an area of several thousand square miles of Eastern Ontario, including Ottawa, Brockville, and Kingston, an extensive area in southern Quebec, northern New York, and northern New England (including parts of Vermont, New Hampshire and Maine).

Farther to the south, southern Ontario and western New York, as well as much of the Appalachian region from Tennessee northward, received heavy rain and severe flooding, while further east, the Canadian Maritimes mostly received heavy snow.
Exacerbating the problem was a steep drop in temperature that immediately followed the passage of the freezing rain, which combined with the extreme power outages led to numerous indirect deaths due to carbon monoxide poisoning from generators and other sources as people desperately tried to remain warm.
On January 4, 1998, an upper level low system stalled over the Great Lakes, pumping warm and moist air from the Gulf of Mexico toward the upper St. Lawrence Valley. The upper flow then turned eastward, bringing this air mass down toward the Bay of Fundy. At the same time, a high pressure center was sitting farther north in Labrador, keeping an easterly flow of very cold air near the surface. An unusually strong Bermuda high pressure area was anchored over the Atlantic Ocean, which prevented these systems from moving further to the east, as most winter storms do when they pass over the Great Lakes–St. Lawrence region.
A series of surface low pressure systems passed in this atmospheric circulation between January 5 and January 10, 1998. For more than 80 hours, steady freezing rain and drizzle fell over an area of several thousand square miles of Eastern Ontario, including Ottawa, Brockville, and Kingston, an extensive area in southern Quebec, northern New York, and northern New England (including parts of Vermont, New Hampshire and Maine).
Farther to the south, southern Ontario and western New York, as well as much of the Appalachian region from Tennessee northward, received heavy rain and severe flooding, while further east, the Canadian Maritimes mostly received heavy snow. Exacerbating the problem was a steep drop in temperature that immediately followed the passage of the freezing rain, which combined with the extreme power outages led to numerous indirect deaths due to carbon monoxide poisoning from generators and other sources as people desperately tried to remain warm.
January 1998 North American ice storm