The Canadian Hurricane Center projected Lee would make landfall in Nova Scotia after 1800 GMT Saturday or perhaps later in New Brunswick with winds below hurricane force.
The potential path could take the storm right into the Bay of Fundy, which separates the two provinces and has one of the highest tides in the world, with the difference between high and low tides as much as 12 metres, or 16m at the head of the bay.Â
Bands from the storm could still be over the bay during a high tide early on Sunday morning.
The United States National Hurricane Center issued a tropical storm warning for hundreds of kilometres of coastline from Massachusetts to Nova Scotia, affecting some nine million people.
Surges of 30 to 90cm are expected for much of New England, according to the National Hurricane Center.
Lee is also expected to generate rainfall of five to 12.5cm with tropical force winds projected for coastal areas.
In anticipation, US President Joe Biden's administration issued an emergency declaration for Maine, providing federal assistance for the state ahead of the storm.
"We encourage all of those in the path of this large and dangerous storm to remain alert," White Press Secretary Karine Jean-Pierre told a press briefing.
Lee has been churning as a large hurricane over the Atlantic for more than a week, briefly threatening Bermuda but mostly harmless for anyone on land.
By Friday night, the storm was packing sustained winds of close to 130km/h and was "expected to be a very large and dangerous storm when it reaches eastern New England and Atlantic Canada", the National Weather Service said.
This marks the second year in a row such a powerful storm has reached Canada after Fiona ripped into eastern Canada a year ago.
