The balmy autumn weather will stay around for a while - if you're in the North Island.

Phillip Duncan from WeatherWatch said temperatures in the upper North Island would stay in the low to mid 20s this week and would remain above average for the rest of the month.

"It is unbelievably warm. Several places are up to 10 degrees above average for the second week," Duncan said. "This feels like March or late February, not May."

But westerly winds were creating havoc further south, Duncan said.

Advertisement

Today and tomorrow, heavy rain is expected to hit the west of the South Island. A strong wind warning is in place for the Canterbury high country, coastal Southland, Stewart Island and Clutha. Westerly and northwesterly gales were expected in Marlborough, Otago and Canterbury.