The weather forecast for August in Washington is usually no mystery at all: hot and humid, with a chance of thunderstorms. This year the forecast has been pretty much true to form. But one of the people who gave the forecast this month has been completely different.

And nobody's telling who he is.

The newest voice in telephone forecasting called himself the "Weather Wizard." Along with the standard forecast, he dispensed early morning cheeriness and homespun wisdom.

During the Communications Workers of America's strike against AT & T, the company's management personnel did numerous jobs normally performed by the people they supervise, including giving the recorded weather forecast. The usual prim, proper voice of an operator gave way to various management types, each of whom had his or her own style. But the one who has received the most attention is the Wiz.

"Good morning, Metro Washington," he began in an upbeat voice. "Welcome to the wonderful world of the Weather Wizard." After giving the National Airport temperature and the barometric pressure and telling us just how much humidity to expect that day, he wound up with a message that was the verbal equivalent of a yellow smile button:

* "It's gorgeous out there! Get out and have some fun in the sun!"

* Spoken quietly: "Let Friday be gentle to you."

* Early one Monday morning: "Some folks call it blue Monday, but the Wiz says, 'Today can be anything you want it to be.' Let's make it a superb day."

* "The Wiz hopes the jam on your toast is the only jam you have today."

* "Let a smile be your umbrella or else you'll have wet feet."

The Wiz was even heard on radio station Q107's Elliott and Woodside morning show last week. "Nothing is sacred to us," Scott Woodside said with a laugh.

The zany radio pair stumbled into the wonderful world of the Weather Wizard when an unsuspecting Jim Elliott dialed 936-1212 before venturing out onto the golf course one day. Elliott was so amused he had the station's engineer record the forecast. Later, he and Woodside broadcast the Wiz. They urged their listeners to call the phone company and ask it to keep the wizardry going even after the strike was settled.

"We got an excellent response," said Woodside. "People were calling us up saying, 'Give him the job, give him the job.' "

But who is this mystery man? No one at C & P would tell. "He is only one of a number of people who are working very hard during the strike," said C & P spokesman Web Chamberlin.

Chamberlin added that recording the weather was not the Wiz's regular job. He said there had been a number of calls asking who the Wiz was and if he could be interviewed. Chamberlin said he refused all of them.

"The phone company should be promoting that guy," Scott Woodside said. "Usually the people giving the weather sound like they're on their last leg. They put you half to sleep. But this guy has flair and personality."