In Auckland - where the mens' ASB Classic tennis is taking place this week - it will also be cloudy, with fresh south-westerly winds and a high of 22C, Sparks said.
Best weather in BOP, East Coast
Holidaymakers in Bay of Plenty, Gisborne and Hawke's Bay will be smiling. They have the best of the country's weather today, with sunshine expected.
It will be a warm day for those on the east coast - temperatures are expected to reach 26C in Gisborne and 28C in Napier.
Overnight gales in southern Hawke's Bay and Northern Wairarapa had eased this morning, she said.
Winds had also eased further north, where a bush fire destroyed a house and lead to evacuations at Mahanga on the Mahia Peninsula last night. Firefighters are still at the scene this morning.
Conditions also appear favourable for firefighters battling a scrub fire at Mt Horrible, near Arthur's Pass.
A nor-wester would turn south-westerly later today, but it was not too windy, she said.
Some rain could be expected, but it was usually drier on the eastern side of the main divide, where the fire was located.
Forecast
Auckland
Today: Cloud periods and fresh south-westerlies. 22C
Tomorrow: Often cloudy, chance shower. 23C
Hamilton
Today: Cloudy periods. 22C
Tomorrow: Often cloudy, a few showers. 24C
Tauranga
Today: Morning cloud followed by sunshine. 24C
Tomorrow: Cloudy periods, chance shower. 27C
Napier
Today: Fine. 28C
Tomorrow: Fine. 29C
Wellington
Today: Few showers, mainly evening. 22C
Tomorrow: Cloudy periods, few early showers. 21C
Nelson
Today: Mainly fine. Chance evening rain. 23C
Tomorrow: Mainly fine. 25C
Christchurch
Today: Cloudy periods, brief afternoon rain. 17C
Tomorrow: Cloudy periods. 20C
Dunedin
Today: Cloudy periods, few afternoon showers. 16C
Tomorrow: Cloudy periods. 19C
Queenstown
Today: Often cloudy, with a period of afternoon rain. 21C
Tomorrow: Fine apart from some morning cloud. 24C