"It should be a really nice day for most people in most areas but there may be a few showers around Auckland and north of Auckland," he said.
"Some inland areas may also be affected by isolated showers. People heading to the beach should have a really good day."
Temperatures throughout the North Island are expected to rise for Boxing Day.
Hamiltonians can expect lots of sun around 26C. Temperatures in Auckland are expected to rise to 25C on Boxing Day from 23C the day before.
The heatwave, which sent December temperature records tumbling throughout the South Island on Monday, yesterday gave the North Island a brief blast of unusually hot weather before Christmas.
Whakatane sweltered in 31C, the hottest of the day, while Hastings hit 30.7C and Napier 30.5C. Tauranga hit 27C while Auckland remained cooler at 23C.
MetService duty forecaster Claire Flynn said eastern areas of the North Island had glorious sunshine for most of the day - a similar story to southern areas on Monday.
Yesterday was also considerably cooler for the South Island after Christchurch, Oamaru and Dunedin surpassed previous highs and Timaru matched its hottest day ever on Monday.
After Dunedin had a stunning 34.6C on Monday, the southern city rugged up with a cool 17C high yesterday.
Mr Dyason said most areas in the South Island could, however, expect things to heat up for Christmas Day.
The forecast
Kaitaia:
• Christmas Day: Cloudy periods. A few showers, 22C.
• Boxing Day: Fine spells, chance shower, 24C.
Auckland:
• Christmas Day: Fine spells, chance shower. Easterly breezes, 22C.
• Boxing Day: Fine spells, chance shower. Sea breezes, 25C.
Hamilton:
• Christmas Day: Fine spells, chance shower. Light winds, 23C.
• Boxing Day: Fine, light winds, 26C.
Tauranga:
• Christmas Day: Mainly fine. Light winds, sea breezes, 22C.
• Boxing Day: Fine. Light winds, 24C.
Hastings:
• Christmas Day: Fine, cloud increases evening, 24C
• Boxing Day: Fine, some morning/evening cloud, 23C.
Wellington:
• Christmas Day: Morning cloud, then fine. Southerly breezes, 20C.
• Boxing Day: Morning cloud, then fine. Southerly breezes, 20C.