A month of fitful weather, from a low of 33 to a high of 88, has kept those in the heating and cooling business going full blast.

"Our company has started at least 100 units in the last couple of days," said Dave Williams of Home Air Conditioning Co. in Silver Spring. The cold-to-hot swing has his customers confused, however.

A few days ago, Williams said, "people didn't know whether to work on the heater or the air conditioner. We had a bunch of no-heat calls last week."

Soaring temperatures have also given federal office workers a warmer spring than what they had been wishing for.

"The General Services Administration hadn't turned on the air conditioning and it was 85 or 90 degrees in there," said Patrick Korten, a spokesman for the Office of Personnel Management, which shut down at 4 p.m. last Friday because of the heat. "It was excruciating. And you can't open the windows."

Korten, whose agency has overall responsibility for deciding when federal workers get sent home because of weather conditions, said there are rumors that the air conditioning will be turned on today.

But weather officials have all but promised that 1983 won't be the year Washington endured six months of winter only to hopscotch past spring and wilt into an endless humid summer.

"Sure, we're going to have spring," Walter Green, an NWS forecaster who's weathered 17 tropical summers here, said yesterday. The season should settle in when the front passes the Washington area late Wednesday, he said, leaving low- to mid-70-degree air in its wake.

Certainly there were no complaints yesterday about the weather. The high of 81 degrees seemed fit for June or July, except for the mere 53 percent humidity.

A summery high of 80 to 85 was predicted for today, with scattered afternoon thundershowers. The humidity is expected to be more than 50 percent, according to forecasters, with continued afternoon showers Tuesday through Thursday.

But the onset of sticky summer is harder to predict. May should average "generally better than 60 percent humidity," Green said.

Green warned that the town may be shortchanged on spring. To hang onto the season, Washingtonians should hope for a Bermuda high, he said. Then, the warm air from the south will get even warmer as it moves over warm land masses, heating the air, saving the azaleas and prolonging the springtime mood. But the moist high will be accompanied by afternoon thunderstorms.