Teachers, nurses and thousands of other workers are all expected to strike.
The union for senior doctors, the ASMS, says outdoor rallies in Wellington, Christchurch and Dunedin have been cancelled, but rallies will still go ahead in other cities.
The PPTA says the strike cannot be cancelled, but some of the actions are being reviewed due to weather.
It has been estimated that 100,000 people could walk off the job.
More than 36,000 nurses were scheduled to strike from 11am to 3pm, and about 40,000 to 50,000 teachers were to go on strike.
An estimated 11,500 other healthcare workers, including senior doctors, dentists, social workers and others, will join them. Senior doctors were striking only in Auckland, Hamilton, Wellington Christchurch and Dunedin.
MetService has issued rare red-level strong wind warnings issued for Canterbury, Wellington and Wairarapa south of Carterton on Thursday.
The forecaster said the wind presented a threat to life from flying items and falling trees, and would cause widespread damage and significant disruption.
The first warning - for the Canterbury High Country - comes into effect at 1am.
Wellington and Wairarapa's warning comes into effect at 8am Christchurch and the Canterbury Plains at 10am.
At this stage the warnings were in effect until late Thursday afternoon.
