|Category 5 major hurricane (SSHWS/NWS)|
|Formed||August 15, 2027|
|Dissipated||September 3, 2027|
|(Remnant low after August 30)|
|Highest winds||1-minute sustained: |
200 mph (325 km/h)
|Lowest pressure||867 mbar (hPa); 25.6 inHg|
(Worldwide record low)
|Damage||$32.8 billion (2027 USD)|
|Areas affected||Cape Verde, Lesser Antilles, Puerto Rico, North Carolina, Virginia, Maryland, Pennsylvania, New Jersey, New York, New England, Quebec, Atlantic Canada|
|Part of the 2027 Atlantic hurricane season|
Hurricane Sam was the most intense tropical cyclone worldwide in recorded history, with a record low barometric pressure of 867 mbar (hPa; 25.6 inHg). Sam also caused severe damage to North Carolina after striking it as Category 4 hurricane. Sam was the eighteenth named storm, eleventh hurricane, seventh major hurricane, and fourth Category 5 hurricane of the extremely active and record-breaking 2027 Atlantic hurricane season.
On September 9, a tropical wave was first noticed over Western Africa by the National Hurricane Center, which they monitored for possible development over the next 7 days. It drifted off west-southwestward once it emerged off from Africa for the next few days, with no change in thunderstorm activity and organization due to relatively high amounts of wind shear surrounding the disturbance. On September 13 over waning wind shear, the disturbance started to organizing and develop a broad atmospheric convection, but still lacking a center of circulation. On September 15 after making a sharp turn toward the west-northwest, the NHC detected a well-defined center of circulation and thus, it was upgraded to Tropical Depression Twenty at 12:00 UTC.
The tropical depression organized and began to acquire banding features near the center of the storm while going on a west-northwestward trajectory, and was upgraded into a tropical storm on September 16 at 00:00 UTC; the NHC assigning the name Sam. Sam then began intensifying more rapidly in low to moderate wind shear, and developed an eye-like feature 12 hours after it became a tropical storm. The very well-organized storm was upgraded into a hurricane at 18:00 UTC. Sam had maximum sustained winds of 85 mph (140 km/h) and a minimum pressure of around 977 mbar (hPa) on September 17 at 12:00 UTC. Afterward, it started to gradually weaken due to an increase in wind shear, and Sam was downgraded to a tropical storm on September 18 at 06:00 UTC.
Shortly after, when the wind shear quickly abated, a period of rapid intensification fueled by very warm temperatures of around 88 °F (31 °C), causing Sam to go from tropical storm to a Category 4 hurricane in just 18 hours from September 18, 12:00 UTC to September 19, 06:00 UTC. It also developed a complete eyewall of 20 mi in diameter surrounding the hurricane’s core. The hurricane held C4 status for 12 hours while undergoing rapid intensification, until it became a Category 5 hurricane at 18:00 UTC that day. The hurricane continued to rapidly grow in size and deepen in pressure, still over low wind shear and very warm waters.
Impact and aftermath