WASHINGTON — Ahead of what would turn out to be a potentially record-breaking hurricane season, the National Weather Service had 216 vacant positions it could not fill due to a governmentwide hiring freeze imposed by the Trump administration, according to a recently released document.

Some of those Weather Service vacancies listed in the document, obtained by the Sierra Club through a Freedom of Information Act and shared with The Washington Post, were in locations that would be hit by the major hurricanes that barreled through the Gulf of Mexico and Caribbean.

Staffing levels at the federal government’s weather bureau, responsible for tracking hurricanes and warning the public about hazardous weather, have fallen since 2010 when the agency employed more than 3,800 nonmanagerial and nonsupervisory employees. Staffing had declined so much that the Government Accountability Office wrote in May that employees were challenged in their ability ‘‘to complete key tasks.’’

The Weather Service’s head count finally stabilized in 2016, with the forecasting agency starting and ending the year with about 3,400 on-the-ground workers.

But the staffing dip resumed in 2017, falling from 3,425 in December to 3,368 in August, according to data from the National Weather Service Employees Organization, a union representing meteorologists and other NWS employees.

‘‘There’s no question that the hiring freeze had an effect,’’ said Dan Sobien, NWSEO president. ‘‘But really it was the straw that broke the camel’s back.’’

He added, ‘‘The camel was already weighed down to the ground.’’

The National Oceanic and Atmospheric Administration, the Weather Service’s parent agency, said the hiring freeze played a part in the recent decline in the agency’s ranks ahead of the triplet of intense storms — Hurricanes Harvey, Irma, and Maria.

‘‘Yes, the hiring freeze was a contributing factor’’ for renewing that decline, NOAA spokesman Christopher Vaccaro wrote in an e-mail.

But NOAA said its forecasting ability was not hampered by the shrunken staff.

‘‘As already demonstrated during Harvey, Irma, Jose, and Maria, NOAA is prepared for the hurricane season and is operating at full tempo,’’ Vaccaro said. ‘‘Our forecasters at NOAA’s National Hurricane Center, local Weather Service offices, and river forecast centers and elsewhere in the agency are fulfilling the agency’s mission of protecting lives and property as they issue timely and accurate forecasts.’’

The Weather Service said that 248 positions remain vacant at the agency. The empty desks are not limited to low-level employees.