The worst of Friday afternoon's storm was over by 6.30pm, but travellers escaping on Christmas holidays or for the weekend remained stranded at the airport following dozens of flight cancellations.

Despite warnings issued for "dangerous" thunderstorms across eastern NSW being downgraded on Friday afternoon, a spokeswoman for the airport said 62 arriving flights and 65 departing flights had been cancelled as of 7pm, and urged passengers to check with their airlines for flight status updates.

Storm warnings were downgraded from "dangerous" to "severe" on Friday afternoon. Credit:Nick Moir

Despite earlier major traffic delays, the roads and public transport had significantly eased just after 7pm. Motorists were still advised to take extreme care on the roads, slow down and never drive through floodwaters.

A woman was arrested for refusing to undertake a breath test after a crash on the Harbour Bridge at 4.30pm, when the Mitsubishi Mirage she was driving hit a stationary vehicle, causing three lanes on the bridge to close, affecting traffic in both directions. The woman, 40, was charged with driving recklessly or furiously, at a speed or in a way that caused danger.