A warning for commuters as Wellington braces for what could be the biggest disruption to public transport the city has ever seen.

Thousands are expected to flock to ANZAC centenary events in the Capital this Friday and Saturday.

That's prompted Greater Wellington Regional Council chair Fran Wilde to issue a warning, urging commuters to plan carefully and allow plenty of time.

She says people can't simply treat this weekend as a typical big occasion.

She's urging people to use public transport, or if they have to drive, consider carpooling as car parking will be at a premium.

Extra early morning trains are being put on to get people to the dawn service on Saturday.