JohnK, a valid point, but from previous occurrences, the airlines want to get everyone on board so that the minute ATC says 'you're right to go', they are.
QF548 departed 22 minutes late on Sunday 5 November at 1927 hours from SYD with BNE arrival suggested as 2015 hours, 40 minutes late.
Looking up the BOM site, Ballina NSW has had 92mm of rain since 0900 this morning including 53mm (more than two inches on the old scale) between 1919 and 2000, 41 minutes. That's a lot, especially for we Mexicans relatively unused to such torrents. No wonder flights were delayed.