MetService communications meteorologist Lisa Murray said tropical weather systems north of New Zealand had led to muggy and humid conditions.
"That's generally why we're having - especially in northern areas - this warm February.
"It's really the overnight temperatures that are contributing to that. We've had this really warm, humid air from these different systems in the tropics that have pushed this air down over [to us]."
Ms Murray said some places were seeing their long-term temperature average (which includes both day and overnight temperatures) on track to beat previous February records.
Hamilton, Wellington and Dunedin were on track to beat their February long-term records. However, with a few days left in the month, including the extra 29th day on Monday, things could change for other places. NZME
High temperatures yesterday:
* Auckland: 24.3C
* Napier: 29C
* Hastings: 31C
* Hamilton: 25.9C
* Tauranga: 25.1C
* Wellington: 23.9C
* Christchurch: 32.8C (hottest in the country)
* Whangarei: 26C
* Rotorua: 24C
* Masterton: 30C
* Dunedin: 24.C
* Blenheim: 31.1C
* Gore: 14.9C (coolest in the country)