The advance forecast for Tuesday -- the day of Waynesburg's annual July 29 all-day festival -- calls for a partly sunny day in the 70-degree range with no rain morning, noon or night.

That would be a nearly perfect forecast for most festivals, but not this one.

Tuesday is the 134th observance of Rain Day, which has been celebrated July 29 every year since 1874. It has rained on 110 of those days -- better than 80 percent of the time.

Fliers, Web sites and announcements always say the event will be held from 11 a.m. until 8 p.m. "rain or shine," though festival organizers root for rain in Waynesburg. The ideal scenario is light rain in the hours before or after the festivities.

Records for recent years show July 29 was rain-free in 2006, 2004, 2003 and 1997.

Waynesburg weather has a history of beating the odds -- rain fell even in 1999 in the midst of a drought. It started falling at 3:17 a.m. July 29, 1999, and stopped at 7:30 a.m. The rainfall totaled one-half inch, which wasn't enough to bring relief to farmers but was more than enough to keep alive the Rain Day tradition.

"July 29th, Rain Day in Waynesburg, is the only holiday anywhere in the world that is not a success unless it rains!" says background information on www.raindayfestival.com -- the Web site.

Since 1979, Rain Day events have been held on High Street, the main street of the Greene County town. Activities sponsored by the Special Events Commission revolve around a street fair in the heart of town, live entertainment on the courthouse steps, arts and crafts booths, hometown food booths and children's games.

Admission is free.

The first scheduled event is the umbrella-decorating contest at 11:30 a.m.

Other events include:

• 1:30 p.m. -- Ginny McClelland Dancers

• 2:30 p.m. -- Barbara Moschetta Dancers

• 3 p.m. -- Miss Greene County Pageant

• 6 p.m. -- Awards for the window decorating contest

• 7 p.m. -- Baby Rain Day winners

Rain Day goes back to 1874 when a farmer doing business in the Daly & Spraggs Drug Store noted that it always rained on July 29, which was his birthday.

Proprietor Byron Daly made a note of that, started keeping records and began making wagers with salesmen who came to his drug store. The wager was a new hat. If it rained on July 29, the drug store owner got a new hat.

His son, attorney John Daly, continued the wager tradition, and in later years the hat bets were made by the mayor of Waynesburg with local, state or national celebrities.

Over the years, hats have been bet and donated by celebrities including Donald Trump, Troy Polamalu, Will Ferrell, Chubby Checker, Fred Rogers, Jay Leno, Mike Love of the Beach Boys, Mario Lemieux, TV weatherman Willard Scott, Johnny Carson, Myron Cope, the Three Stooges, Bob Hope and Bing Crosby.

This year's hat bet is with Pittsburgh Mayor Luke Ravenstahl.