Temperatures have surged over 30C on Tuesday evening in Hawke's Bay - and Wednesday could be even hotter.

WeatherWatch.co.nz head forecaster Philip Duncan said a number of weather stations around Hawke's Bay and Gisborne recorded temperatures of mid to late 20s on Tuesday but some reached 32C.

The heat was caused by warm northwesterlies and sunny skies and continued up until 5pm.

Duncan said 30C highs in April do sometimes occur but he pointed out we're now on "the wrong side of summer for summer-like temperatures".


"The equinox was two weeks ago and that was the point when days and nights were roughly equal, the nights are now longer than the days so summer temperatures should be less likely to occur".

Wairoa, which on Tuesday hit 30C, is forecast to again reach the late 20s on Wednesday.

It was also warmer than average in other parts of New Zealand including Southland where it was up to 21C at 5pm today - just 90 minutes shy of sunset.

The average high for Invercargill in April is 15 degrees.

In the coming week, temperatures in Hawke's Bay will drop by up to 10C in the day on some days.

But it's Southland, Otago and alpine areas of both islands in for a more real wake up call this weekend and early next week if the latest data pans out, Duncan said.

"Our forecasts for temperatures show daytime highs this weekend in the far south may be just 10 to 13 degrees at the warmest point of the day," Duncan said.

"However next Tuesday the latest WeatherWatch.co.nz forecasts show highs of only 8 to 11 degrees across Dunedin, Queenstown and Invercargill."