Auckland is set to begin its anniversary weekend with some extreme wet weather, as an incoming "moisture plume" approaches the upper North Island.

"A sub-tropical moisture plume isn't what Auckland ordered for its anniversary weekend but Mother Nature didn't get the memo," NIWA Weather tweeted alongside a graphic of the atmospheric weather system.

MetService has also issued a number of severe weather warnings and watches for the upper North Island in the coming days.

"If you were planning to get away on Friday it might be worth delaying," the forecaster tweeted.

A heavy rain warning is in place for Northland from 10pm tonight to 10pm tomorrow, the Coromandel Peninsula from 10am tomorrow to 10am Saturday, and the Bay of Plenty west of Whakatane from 4pm tomorrow to 4pm Saturday.

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"Heavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous," MetService warn.

A heavy rain watch is in place for Auckland about and north of Whangaparaoa Peninsula, also Great Barrier Island, from 7am to 10pm tomorrow, and for Mount Taranaki from 4pm tomorrow to 4am Saturday.

A strong wind watch is in place for Auckland from 7am to 10pm tomorrow - and it could see the Harbour Bridge closed tomorrow afternoon under a "red alert", Waka Kotahi warn.

"The safety of road users is our top priority and we won't hesitate to reduce speeds, close lanes or close the bridge if necessary."

MetService advises people to keep up with the latest forecasts in case changes are made or more areas are added.