Sir Elton John's concert at Mt Smart Stadium has been canned while residents in flood-prone areas of West Auckland are being told to prepare to evacuate.

The concert was cancelled at 7.17pm due to the atrocious weather hitting the city.

The decision was made just a few minutes before the singer was due to take the stage.

The decision means disappointment for 40,000 fans at the stadium who now face a difficult night getting home due to limited public transport options.

In Tauranga, the One Love festival posted to Facebook saying they have set up tents inside for the festival's campers to enjoy over the weekend.

Meanwhile Auckland Emergency Management says the weather across Tāmaki Makaurau is continuing to worsen and residents in flood-prone areas should prepare to evacuate.

Residents in flood-prone areas of West Auckland are being asked to prepare to evacuate as bad weather causes power cuts and car crashes across Tāmaki Makaurau, with a severe thunderstorm watch in place for the north of the country.

Auckland Emergency Management says the severe weather across the city was worsening and it was trying to assess what action was needed.

If lives were at risk, residents should phone 111 immediately, it says in a social media post.

It also asked people to check on neighbours, friends and family members but not to put themselves in danger to do so.

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- RNZ.