Weatherwatch forecaster Phillip Duncan said tropical air from the remnants of Evan would make it seem warmer than the actual temperatures - around the mid-20s - across the North Island.
"The 'feels-like' temperature will be in the low to mid-30s in these regions, especially if the sun comes out for a bit as well," he said.
The capital looked set to have a mostly fine day, with highs in the mid-20s and morning showers clearing.
Both forecasters predicted the South Island was the place to be, the Mainland enjoying highs of 30C and above in central Otago and inland Canterbury, with clear skies and light winds.
MetService forecaster Brooke Lockhart said former tropical cyclone Evan was weakening as it approached New Zealand.