Land interaction weakened the storm somewhat, although it was able to quickly recover and later peaked that night with sustained winds of 175 mph (280 km/h) and a pressure of 908 mbar (26.8 inHg).

Structural changes in the hurricane as it moved further north and close to the Outer Banks in the United States ultimately caused Maria to weaken quickly.

As the system was an imminent threat to land despite the center not appearing to be well-defined, the NHC upgraded it to Potential Tropical Cyclone Fifteen at 12:00 UTC, while situated 665 mi (1,070 km) east of Barbados.

Sea surface temperatures of 84 °F (29 °C), low wind shear, and ample moisture were anticipated to foster strengthening to hurricane-status before the system reached the Lesser Antilles.

[5] A central dense overcast and favorable outflow developed atop the center of circulation, which enabled Maria to become further organized throughout the early morning hours of September 17.

[11] Considerable lightning activity was identified within the hurricane's core early on September 18 and statistical models indicated a high probability of rapid intensification.

[14] Rapid intensification culminated late on September 18, with Maria achieving Category 5 status just 15 mi (25 km) east-southeast of Dominica.

Maximum sustained winds reached 175 mph (280 km/h), and the storm's central pressure bottomed out at 908 mbar (hPa; 26.81 inHg); this ranks it as the eleventh-most intense Atlantic hurricane since reliable records began.

Interaction with the mountainous terrain resulted in substantial weakening; sustained winds fell to 110 mph (175 km/h) and the central pressure rose to 959 mbars (hPa; 28.32 inHg).

[28] During the afternoon of September 21, the system traversed the Navidad and Silver banks north of the Dominican Republic; shoaling from the region's shallow waters temporarily interfered with measurements of surface winds.

[5] An increase in southwesterly wind shear prompted gradual weakening of the hurricane, starting with restriction of banding features and later degradation of the eyewall.

[33] Maria fluctuated in organization throughout the day of September 23, with its eye periodically clearing and becoming cloud-filled; it maintained Category 3 hurricane strength during this phase.

[36][37] By this time, Maria's trajectory had shifted almost due north between the aforementioned ridge and a cut-off low that was located over the eastern Gulf of Mexico.

[39] However, a sustained convective burst maintained Maria's hurricane intensity,[5][40] with banding features evident on the eastern part of the circulation.