SAN JUAN, Puerto Rico (AP) — The outer bands of Hurricane Humberto lashed Bermuda on Tuesday as it approached the tiny British territory, with newly formed Hurricane Imelda following closely behind.

A hurricane warning was in effect for the island in the north Atlantic as forecasters advised of dangerous seas, strong winds and heavy rain.

Humberto was located about 295 miles west-northwest of Bermuda. The Category 1 storm had maximum sustained winds of 80 mph and was moving north at 17 mph, according to the National Hurricane Center in Miami.

Humberto was a Category 4 storm on Monday, but was quickly losing strength and was forecast to dissipate by Wednesday.

Humberto was expected to pass well west and north of Bermuda on Tuesday and Wednesday morning, while Imelda was expected to pass near or over the island late Wednesday as a Category 2 hurricane, according to the Bermuda Weather Service.

“I cannot overstate the seriousness of this threat,” Michael Weeks, Bermuda’s minister of national security, said of Imelda. “This is not, I must stress, a passing squall.”

He said Bermuda would endure sustained hurricane-force winds for up to six hours starting late Wednesday.

Weeks announced at a news conference that the island’s international airport would close on Wednesday, as would schools and government offices.

He said residents should have all storm preparations completed by noon Wednesday.

“Imelda has the potential to damage and disrupt our island significantly,” he said.