PHILLIP ISLAND, AUSTRALIA, OCT 15 - The 2010 Australian Grand Prix was on a weather hold after heavy overnight rains, and steady rain throughout the day, made the seaside Phillip Island circuit unrideable. But a decision to begin on-track activities was taken by race direction at 2:30 p.m., 11:30 p.m. EDT Thursday.The first practice session, for 125's, was to begin at 2:40 pm. local time. MotoGP (3:50-4:50) and Moto2 (5:00-6:00) practices will follow.The rain began late last night and has continued all day, with temperatures plummeting to 50 degrees, aided by a biting wind off the Bass Straits.The decision to postpone practice was taken late in the morning, after a serious crash on the front straight during qualifying for an Australian national race.The 125cc practice, scheduled for 12:40 p.m., was postponed with an announcement planned for 1:30 p.m. That deadline came and went and a second advisory was issued which said the next decision by race management would be taken at 2:30 p.m., 11:30 p.m. EDT Thursday.The forecast for Saturday is similar, with an 80% chance of rain, along with hail. Sunday's forecast is slightly better, though rain is expected.