A 60-foot tree toppled by wind shortly after noon fell across two parked cars and one in motion on T Street NW. No injuries were reported. Police closed the block until crews could clear the tree. (Brian Murphy/For The Washington Post)

On the windiest day of the month in the Washington region, Sunday’s winds and gusts proved damaging and deadly.

A hiker was killed by a falling tree on the Appalachian Trail. Although what caused the tree to fall was not conclusively known, it came down during a time of high, gusty winds, a spokeswoman for the National Park Service said.

In the District, at least one tree toppled in the 1600 block of ­T Street NW shortly after noon, falling across two parked cars and one that was moving, according to residents of the neighborhood.

No injuries were reported in that incident.

On Constitution Avenue NW, where the District’s annual St. Patrick’s Day parade was held, “the wind made it very cold until the sun came out,” said Alexandria Mayor William D. Euille (D), who was listed as a participant along with local government figures from throughout the District, Maryland and Virginia.

Theresa Cullinane, who was honored as Gael of the year, said it was “a little cool, but it didn’t dampen the spirits in any way.” Watching the flapping of the flag that hung over the parade route was “very impressive,” Cullinane said with a hint of wryness.

Neither Colleen Cohan, a parade official, nor Allison Wetterauw, a division marshal, thought the wind had much adverse effect, although Wetterauw jokingly allowed that she “could have used a little more hair spray.”

Even for March, the wind was notable. At Reagan National Airport, sustained winds reached 30 mph, and a gust was clocked at 45 mph, according to the National Weather Service. Dulles International Airport was even windier, with a 36-mph top wind and a 47-mph gust.

Before Sunday, the month’s top wind at National was 26 mph, on March 2, with a 35-mph gust.

It was the windiest day at National since Feb. 15, when gauges showed a 39-mph wind and a ­56-mph gust.

The hiker killed on the trail was identified by a Park Service spokeswoman as Jason Parish, 36, of Philadelphia. She said the incident occurred in Washington County, Md., about 70 miles northwest of the District.

About a dozen hikers and a Park Service ranger were near the Ed Garvey shelter when the tree fell, and the ranger gave emergency aid, but to no avail, said spokeswoman Jenny Anzelmo-Sarles.

She said Parish was with two companions and that he began hiking north on Friday in the Harpers Ferry area.

When the tree fell on T Street NW, there was at least one person to hear it. Pete Miller, who was sitting on the ground floor of his house, said he heard what sounded like icicles dropping from the roof.

He found that the tree had fallen across parked cars, with its upper branches striking a moving car. Its occupants were uninjured, Miller said. They indicated, he said, that the parked cars took most of the shock, and the upper branches seemed to fall “very slowly.”