Thursday’s decision to shut down most play at the Australian Open on the third day of a massive heatwave was made with both players and spectators in mind, the Australian Open tournament director Craig Tiley told DPA.

“I have to decide for entire tournament,” said Mr. Tiley. “And this is the right decision for our fans and the players.” The decision at 1:50 p.m. (0350 GMT) stopped afternoon play on outside courts. Play was to continue on the showcourt with moveable roofs — Rod Laver and Hisense Arenas — with their roofs to be closed for ensuing matches.

Melbourne has sweltered in temperatures of more than 40 degrees for four days in a row, conditions not experienced in 100 years.

Mr. Tiley said that despite the addition of 3,200 square metres of shaded areas around the grounds of Melbourne Park, conditions were just too extreme to continue under the complicated formula which takes into account, temperature, humidity, wind and other factors to produce an index reading.

The trip-wire number has never been revealed, but Mr. Tiley said the limits were breached.

“This is a well-researched policy, not something we made up overnight,” the experienced official told DPA. “We take medical and other factors into consideration from some of the best authorities in the world.

“We invest in a weather bureau on site. When humidity and air temps reach unacceptable levels, we invoke the policy.

“Today we got a forecast that conditions would stay in the high range. The moment I knew that I made the call right away. Melbourne can be a place of all four seasons in the same day. It would have been easier if this had happened next week, when we would have mainly been playing indoors. But we do have two courts with roofs.

“For as many players who don’t want to play, we have others saying ’we are pros and we should be prepared. We play in hot conditions all over the world.’” Mr. Tiley said that over Monday and Tuesday, ground entry ticket sales dropped but “(showcourt) ticket holders know that the roofs will be closed if things get really bad”.

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