Wet and windy weather may affect travel in Auckland and Northland tonight

Waka Kotahi's warning winds up to 100 kilometres an hour could affect drivers on the Harbour Bridge.

It says they won't hesitate to close the bridge if necessary.

The strongest gusts are expected between midnight and 6am ... and high-sided vehicles and motorcycles should use State Highways 16 and 18 instead.

A heavy rain warning is in place for Northland - and motorists should be on the look-out for surface flooding and slips.