People with homes and businesses along the west coast had been able to return only during daylight hours over concerns that ash and superheated clouds of debris could spew from the mountain at any time.
But the Montserrat Volcano Observatory says that a partial dome collapse on Feb. 11 significantly reduced the hazard, making round-the-clock access to the communities safe.
Many parts of the island are still off limits to visitors and former residents at all times of the day and night.
Approximately two-thirds of the island has been declared an exclusion zone because of the volcanic hazard.
The volcano roared to life in July 1995 for the first time in recorded history. It spewed huge plumes of ash and molten lava into the sky for several weeks, raining down on the British overseas territory.
The island’s capital of Plymouth was subsequently destroyed and buried beneath a thick blanket of ash. A new provisional capital is being constructed at the other end of the island.