Hurricane Douglas passed north of the main Hawaiian Islands on Sunday, and on Monday was moving along Papaha­naumokuakea Marine National Monument, the remote Northwestern Hawaiian isle chain.

Hawaii residents dodged what weather officials are calling a historically close call when Douglas passed as near as 30 miles north of Oahu on Sunday evening.

As of 5 p.m. Monday the storm had been downgraded from a hurricane to a tropical storm, with maximum sustained winds of 70 mph. Douglas was about 255 miles west-northwest of Lihue and 200 miles east- southeast of French Frigate Shoals, traveling west at about 17 mph.

A tropical storm warning remained in effect Monday evening for portions of Pa­pahanaumokuakea — from Nihoa to Maro Reef. In addition, a tropical storm watch remained in effect for the area from Maro Reef to Lisianski.

A tropical storm warning means tropical storm conditions are expected within the next 12 to 24 hours, and a tropical storm watch means tropical storm conditions are possible within 36 to 48 hours.

“We’re keeping our fingers crossed,” said Athline Clark, NOAA’s superintendent of Papahanaumoku­akea Marine National Monument. “We will continue to monitor the storm.”

Papahanaumokuakea, home to thousands of species of fish and endangered wildlife found nowhere else on Earth, celebrates its 10th anniversary as a designated World Heritage site this month.

Clark said some personnel are stationed at Midway and Kure atolls at the northwestern end of the monument, and that Douglas is expected to slow to a tropical depression by the time it reaches those areas. Officials will, however, keep an eye on French Frigate Shoals, which is home to abundant wildlife and one of the most significant coral reef systems at the monument.

The U.S. Fish and Wildlife Service is working with the National Oceanic and Atmospheric Administration and state to monitor any potential impacts in the area, according to USFWS Superintendent Jared Underwood.

“While it is not seabird nesting season in Papaha­naumokuakea, there could be immediate impacts to sea turtles and monk seals who are nesting and pupping right now,” wrote Underwood in an email. “All terrestrial species would be affected if we lose islands or parts of islands to erosion such as during Hurricane Walaka. Marine resources could also be affected as they were in 2018.”

In October 2018, Hurricane Walaka, a Category 3 storm, ripped through the monument, directly passing over French Frigate Shoals, wiping out East Island, a nesting site for threatened green sea turtles, and flooding burrows of nesting seabirds while sweeping away vegetation.

NOAA scientists returning from expedition to the monument last summer discovered that Rapture Reef, previously one of the most beautiful, diverse reefs in the isles, had become a wasteland of coral rubble.

Weather officials Monday also said Hurricane Douglas is the closest a hurricane has come to Oahu for more than 60 years — even closer than Hurricane Dot in 1959.

According to preliminary data from the Hurricane Hunters and weather radars, the center of Douglas passed about 30 miles north of Kahuku at about 7 p.m. Sunday. This appears to be closer than Hurricane Dot, which passed about 60 miles southwest of the Waianae coast of Oahu before making landfall on Kauai in August 1959.

Tropical storm-force winds were just within about 10 miles off Oahu’s northern tip, according to satellite, radar and aircraft reconnaissance data.

Fortunately, officials said, Douglas encountered wind shear as it approached the isles, which were on the left side of the hurricane’s track during its west-northwest trajectory, keeping the worst of the storm’s impacts just offshore of all isles.

Highest rainfall amounts recorded over 24 hours, ending 8 a.m. Monday, were 5.16 inches at Puu Kukui in Maui County; 3.69 inches at Kapahi, Kauai County; and 2.76 inches at Punaluu on Oahu. Wind speeds reached up to 70 mph at Nene Cabin on Hawaii island; 69 mph at Kula, Maui; 55 mph at Kuakoala on Oahu; and 39 mph at Barking Sands, Kauai.