By Melanie Burton

MELBOURNE (Reuters) - Fans frolicked in front of mist fans dotted around Melbourne Park on Tuesday as Australian Open organizers breathed a sigh of relief that this year's tournament might escape the worst excesses of the weather.

The Melbourne scorcher is a rite of passage for players and fans at the year's first grand slam, and temperatures above the 40 degrees Celsius mark in 2009 and 2014 forced the cancellation of matches and the invocation of the extreme heat policy.

The two-week tournament moved into its second day of play on Tuesday and while it was undoubtedly very hot, the mercury peaked at 37.8C, leaving tournament meteorologist Bob Leighton confident there would be no need for special measures.

"We've had two years with severe heatwaves in the past 10 years. So far it's a fairly normal year," he told Reuters.

"Tomorrow we're going down to the low twenties and there should be a couple of warmer days from next weekend -- Sunday and Monday."

On the air-conditioned Rod Laver Arena, players such as Serena Williams and Rafa Nadal breezed through their matches despite the stifling conditions outside.

"It was fine. I didn't have a problem with the heat," Williams told reporters.

The duo were the singles champions in 2009, when the heatwave that hit the tournament resulted in the Black Saturday bushfires that blazed across Victoria a few weeks later, claiming 173 lives.

In 2014, a ball boy and player fainted during a match, and organizers were criticized for allowing the tournament to continue. Since then, they have planted trees and added 3,200 square meters of shade in the redevelopment of Margaret Court.

KONTA MEASURED

Temperature, wind direction and humidity are taken into account under the extreme heat policy that leaves it to the discretion of the referee to suspend play and close the roofs.

For Australian-born Briton Johanna Konta, who won the Sydney International last week and beat Kirsten Flipkens in the first match on the Margaret Court Arena, Tuesday's heat was all relative.

"It was hot, but last week in Sydney, we experienced something a lot hotter," she said. "So I think it was almost cool in comparison."

While players may have found conditions tolerable on Tuesday, they were still keen to escape the heat.

"I don't know how much degrees there was, but I felt okay," said Czech Karolina Pliskova, who raced to victory against Spain's Sara Tormo on Rod Laver Arena.

"But I was there an hour, I think if I had stayed longer, it would have been worse."

Anne Williams, a spectator from rural Victoria attending the tournament for the first time, had sympathy for Rogerio Dutra Silva and Jared Donaldson, who slugged it out for three hours on the exposed Court Five in the full heat of the afternoon.

"Some of the players will be used to the heat, and they may have an advantage. Others, the Eastern Europeans for example, may find it tougher," she opined from beneath the brim of her straw hat.

"(British world number one) Andy Murray's been here loads of times, at least he knows what he's in for."

(Editing by John O'Brien)