Category 5 Atlantic hurricane
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Hurricane Lee was a long-lived and intense tropical cyclone which impacted Bermuda, the Northeastern United States, and Eastern Canada in September 2023. The twelfth named storm, fourth hurricane, and third major hurricane of the 2023 Atlantic hurricane season, Lee formed on September 5 from a tropical wave that had moved offshore from West Africa into the tropical Atlantic a few days earlier. A strong steering current caused the storm to track northwestward, far from the Northern Leeward Islands. Highly favorable conditions enabled Lee to rapidly intensify to a Category 5 hurricane on September 7, its winds increased by in 24 hours. This makes it the fifth‑fastest rapid intensification on record in the Atlantic, only behind Hurricane Wilma in 2005, Hurricane Felix in 2007, Hurricane Milton in 2024, and Hurricane Matthew in 2016. Just as quickly however, Lee's strength waned, and it fluctuated in intensity for several days on account of strong wind shear and multiple eyewall replacement cycles. 
On September 13, the system rounded the southwest side of a large ridge of high pressure over the central Atlantic, turned, and accelerated northward. Lee soon entered into an environment of increasing wind shear and moved into increasingly cooler water, causing the system to slowly weaken as it passed near Bermuda and New England, and to undergo the transition into an extratropical cyclone. The cyclone then made landfalls in Nova Scotia, New Brunswick, Prince Edward Island, and in Newfoundland and Labrador, before moving out into the far northern Atlantic on September 18, where it merged with another extratropical low.
Swells generated by Lee caused dangerous surf and rip currents along the entire Atlantic coast of the United States. Strong winds with hurricane‑force gusts caused extensive power outages in the U.S. state of Maine, and in the Canadian provinces of New Brunswick and Nova Scotia. Total damage is estimated at USD$80 million as of 2024. Three storm-related fatalities have been confirmed: a 15-year-old boy drowned in Fernandina Beach, Florida; a 51-year-old man died in Searsport, Maine, when a tree fell onto the car he was in; and a 21-year-old man who was killed when the boat he was in was capsized and sunk by a large wave in Manasquan Inlet, New Jersey.
Meteorological history.
The National Hurricane Center (NHC) began to monitor a tropical wave over West Africa early on September 1. The wave moved offshore into the tropical Atlantic Ocean on September 2, producing disorganized shower and thunderstorm activity, and began to gradually organize. An area of low pressure formed from the wave two days later to the west-southwest of Cabo Verde. On September 5, the low became more organized, with multiple low-level bands developing and the formation of a well-defined center. Consequently, advisories were initiated on Tropical Depression Thirteen at 15:00 UTC that day. Amid favorable conditions for intensification, which included warm sea surface temperatures, moderate wind shear, and moderate mid-level relative humidity, the depression quickly strengthened into Tropical Storm Lee within a few hours.
Lee tracked west-northwestward, steered by a mid-level ridge located to its north, and continued to intensify as it became better organized, with increased convective banding, development of a central dense overcast, and formation of a ragged eye, evident in visible satellite imagery by the following afternoon. By 21:00 UTC on September 6, the system strengthened into a Category 1 hurricane while located far to the east of the Northern Leeward Islands. Explosive intensification began the next day, with Lee reaching Category 2 strength at 15:00 UTC, then reaching Category 4 strength at 21:00 UTC. A few hours later, a hurricane hunters mission into the storm found that it had reached Category 5 strength, and possessed a clear eye surrounded by convective cloud tops with temperatures as low as . By 06:00 UTC on September 8, Lee's maximum sustained winds reached , an increase of in 24 hours, making it the fifth‑fastest intensifying Atlantic hurricane on record, surpassed by only Matthew in 2016, Hurricane Milton in 2024, Felix in 2007, and Wilma in 2005. During this same time period, the hurricane's minimum barometric pressure fell to .
Several hours later, an increase of southwesterly wind shear caused Lee's eye to become cloud-filled and the storm to become more asymmetric. This caused Lee to quickly weaken to a low-end Category 3 hurricane by early on September 9. Later that day, data from a hurricane hunters mission into the storm revealed that Lee was undergoing an eyewall replacement cycle and still being adversely affected by modest vertical wind shear. The mission also observed were peak flight-level winds that were still decreasing, as a result of these findings, the hurricane was downgraded to Category 2 at 03:00 UTC on September 10. Afterwards, as the system was completing its eyewall replacement cycle, the wind shear began to abate, which permitted the new, larger-diameter eye to contract and to grow more symmetric; as a result, Lee intensified to Category 3 strength once again that same day with maximum sustained winds of . Lee's overall appearance improved in the short term, and surface barometric pressure dropped due to the storm growing in size, despite maximum sustained winds remaining relatively consistent. The system underwent two eyewall replacement cycles over the course of the next couple days; and while they caused some fluctuations in its size and intensity, Lee remained a major hurricane throughout.
Lee slowly tracked west-northwestward to northwestward during this time, before turning northward on September 13, moving around the western side of a subtropical ridge situated over the central Atlantic. That same day, the hurricane began to encounter increasing southwesterly shear coupled with dry air entrainment and weakened to Category 2 strength. Despite this, Lee continued to grow in size, with hurricane-force winds extending outward up to 115 mi (185 km) from its center and tropical storm-force winds extending outward up to 240 mi (390 km). Slow weakening continued and Lee was downgraded to a Category 1 hurricane on the morning of September 14, as its eye was no longer apparent in satellite images and deep convection was absent over the southwestern portions of the storm circulation. Later in the day, the system made a close, , pass to the west of Bermuda. As Lee pushed northward, continued dry air entrainment and increasingly strong southerly wind shear displaced the storm's convection to the northern side of the system, weakening it further. These factors caused the hurricane to commence its extratropical transition, which was completed by 09:00 UTC on September 16. Later that day, the center of the cyclone made landfall on Long Island, in Nova Scotia. Then, overnight into September 17, it traversed both New Brunswick and Prince Edward Island while continuing to weaken. The storm crossed northern Newfoundland and moved out into the open north Atlantic on September 18, where it dissipated upon merging with another extratropical low.
Preparations and impact.
Bermuda.
Bermuda received tropical storm watches on September 12, which were later upgraded to warnings on September 13.
Bermuda suffered tropical storm conditions. The House of Assembly moved their September 15 meeting date to September 22. L.F. Wade International Airport reported peak winds of and was closed until September 16. Up to 11,342 people lost power as a result of the storm; and the Devonshire and St. George's bus depots had significant power failures, causing them to be closed until September 16. The Royal Naval Dockyard also suffered damage, causing ferry delays between the Dockyard and St. George's. Total damages in Canada and Bermuda were estimated at USD$30 million.
United States.
A hurricane watch and a tropical storm watch were issued for the New England coastline from Rhode Island to Maine, including Block Island, Martha's Vineyard and Nantucket, on September 13. A storm surge watch was also issued for Cape Cod Bay and Nantucket, although this alert was cancelled when the storm veered further to the east. During the afternoon on September 14, a boat was capsized during a small craft advisory after being hit by a tall wave in New Jersey's Manasquan Inlet, requiring first responders to rescue two people. A 21-year-old man who was also on the boat was killed and his body washed ashore on Point Pleasant Beach on September 24. Rough surf and dangerous rip currents were present along all of the east coast of the United States as Lee passed off the coast, and on September 15, a 15-year-old boy drowned due to rough surf off of Fernandina Beach, Florida. On September 16, all Cape Air flights between Logan International Airport and Hancock County–Bar Harbor Airport were canceled. Total damage in the US is estimated at USD$50 million. 
New York.
New York State Governor Kathy Hochul deployed fifty National Guard members to Long Island in preparation of the storm's arrival. The New York City Emergency Management Department advised coastal communities in the city to review their emergency plans. On September 15, the town of Southampton declared a state of emergency, shutting down coastal roads. The same day, the town of East Hampton prohibited swimming at all beaches. 
Eastern Long Island experienced beach erosion and gusty winds from the storm.
Massachusetts.
In Massachusetts, boats on Nantucket were pulled from the water or were sheltered in protected harbors. All Hy-Line Cruises service was canceled between Martha's Vineyard and Hyannis, and from Martha's Vineyard to Nantucket. The Steamship Authority waived change and cancellation fees for ferries between September 15 and 17. On September 14, Boston Mayor Michelle Wu announced the opening of an emergency operations center. Preparations to place sand bags and flood walls if necessary were also made. The Boston Police and Fire Departments were put on standby. On September 15, Massachusetts Governor Maura Healey announced a state of emergency in response to the cyclone. Healey also announced that 50 members of the Massachusetts National Guard capable of operating high-water vehicles were being activated in anticipation of any potential rescues. Numerous flights were canceled or delayed at Logan International Airport, with some routes being canceled entirely due to high winds. The majority of damage was caused by trees being felled due to a combination of gusty winds and highly saturated ground. In Cohasset, a Cohasset police officer's cruiser was crushed by a falling tree while the officer was outside his cruiser.
Rhode Island.
The Rhode Island Department of Transportation cleaned out storm drains and cut down at risk trees to mitigate flood and wind risk. Rhode Island Lieutenant Governor Sabina Matos reminded municipalities to update their hazard mitigation plans during a press conference with Governor Dan McKee and other state officials. McKee also announced that the "Independent Man" statue atop the Rhode Island State House in Providence was being taken down for repairs due to damage to the dome of the statue before any potential impacts by Lee could put it at risk.
New Hampshire.
New Hampshire Governor Chris Sununu announced that utility crews were being staged across the state to quickly respond to power outages and warned residents to not be complacent. A wind advisory was put into effect for New Hampshire's White Mountains, where wind would be stronger due to elevation. On Mount Washington, gusts reached up to .
Maine.
Maine Governor Janet Mills declared a state of emergency and requested President Joe Biden to issue an emergency disaster declaration for the state, and he did so later that evening. Utility workers from as far as Tennessee were brought into the state to help quickly restore power in case of outages and boat owners were advised to secure their boats by the Maine Harbor Master's Association. The White Mountains in Maine were also put under wind advisory. On September 16, about half of all flights to and from Portland International Jetport were canceled, while most flights were canceled to and from Bangor International Airport due to high winds. The National Park Service also shut down certain areas of Acadia National Park.
On September 16, wind damage occurred across southeastern portions of the state, where trees were down, including some that fell over a portion of SR 11 in Aroostook County, forcing a closure, and more than 92,000 power outages occurred. Maine House Republican leader Billy Bob Faulkingham, along with one other person, were rescued after their boat overturned off of Winter Harbor while they clung to the hull of the vessel until rescue arrived. One person was killed after his vehicle was struck by a falling tree in Searsport. An Ohio man was also injured while driving on SR 11 in Moro Plantation after a downed tree went through his windshield. In Bar Harbor, a whale watching vessel broke free and crashed ashore, forcing authorities to offload of diesel fuel to prevent it from spilling into the ocean. As of the afternoon of September 16,