Just after 2 p.m. yesterday, the hot, heavy skies over Woodbridge Airport turned an ominous shade of gray and, with a flash of lightning and a clap of thunder, it began to rain.

For the pilots gathered in the hangar, it was perfect weather for the occasion. You can't fly in a thunderstorm, and, starting today, you can't fly in and out of Woodbridge Airport.

Yesterday was the last day of operations at the privately owned facility in Prince William County, whose 80 acres soon will to be turned into apartments, offices and a shopping center.

There was an air of melancholy among many of the pilots and employes who came to a goodbye party yesterday at Woodbridge, the sixth-busiest of the 63 general aviation airports in Virginia and one of the most popular training fields for pilots in the Washington area.

After a stand that began almost from the day it opened 20 years ago, Woodbridge Airport has fallen prey to development. Like a rising number of general aviation airports around the nation, the land became too valuable and the opposition of neighbors too great for the field to survive.

"It has been good to me, and I hope it's been good to you," airport owner Charles D. Benn said to a crowd of friends and pilots standing in front of the hangar after the weather cleared.

Benn, who bought Woodbridge in 1970 and sold it last year, is a near-legendary figure among many general aviation buffs in Northern Virginia.

A gruff, colorful 67-year-old who has been flying and teaching pilots for 40 years, Benn said he recently asked himself, "When is enough, enough?"

Before buying Woodbridge, Benn said, he operated with his brother the Washington-Virginia Airport in Baileys Crossroads, which also was sold to a developer.

By yesterday afternoon, only a few of the 113 aircraft based at Woodbridge were tied down along the taxiways, and their owners were preparing to fly them away after the parting ceremony. Most of the pilots were taking their planes to other Northern Virginia airports, including strips at Manassas and Leesburg.

Many of the pilots said that for them, Woodbridge was more than simply a place to park their plane. They said they often would spend hours in the main hangar, regaling one another with flying stories.

"The sad thing is not so much the airport, it was the people who would come here," said Tom Reich, an Arlington resident who based his plane at Woodbridge.

Many at Woodbridge yesterday saw the closing as a grim reminder of what is happening around the country. Between 1974 and last year, more than 1,200 airports closed nationwide, most of them small, general aviation facilities, according to private-pilot groups.

"It's a sad day for general aviation," said Tom Foxworth, a pilot for a major commercial airline who used to keep his personal plane at Woodbridge. "You need little airports like this."

Foxworth's comments were echoed by officials with the Airline Owners and Pilots Association, who said that airports like Woodbridge serve a vital role in the nation's air network by pulling small aircraft away from major airports and providing a training ground.

"Everybody wants training to take place in these small airports," said pilot group senior vice president Edmund Pinto. "Get it away from Dulles; get it away from National."

Not everyone thinks that the Woodbridge closing is cause for dismay. Several hundred residents of the affluent Lake Ridge community, adjacent to the airport, recently signed a petition supporting the rezoning that cleared the way for the airport's closing, according to Prince William County Supervisor Kathleen K. Seefeldt (D-Occoquan). Most of the residents were concerned that a plane could crash on houses or a nearby school.

"The feeling was, sooner or later, there was going to be a disaster," Seefeldt said.

The fears were not unfounded. During the past several years, a total of five people have died in at least two crashes at Woodbridge. The airport's 2,246-foot paved runway, with a large dip in the middle and trees near both ends, had a reputation among pilots for being unforgiving.

"If you could fly in and out of here, you could fly anywhere," said pilot Hal Blank, who said he bought his home in Lake Ridge to be near the airport and now plans to move.

Although Prince William is weighing whether to build a public airport somewhere along the I-95 corridor, Blank said he fears that such a facility could be many years away.

A recent consulting study requested by Prince William concluded that a 5,400-foot paved runway in the eastern end of the county would require at least 600 acres and would cost about $30 million.