This follows a record December 10 for Rotorua. On December 10 the temperature hit 28.4C to become the warmest December day on record for the town, beating an old record of 28.3C on December 28, 2015.
However, MetService meteorologist Andy Best said an accurate prediction for Christmas Day couldn't be made until Sunday.
"Both Rotorua and Tauranga are enjoying the heat today with Rotorua reaching a high of 26C with Tauranga a single digit higher on 27C," Best said.
"Tomorrow [Wednesday] will be slightly cooler for both cities with high cloud forecast. On Thursday things will cool a little more as a low makes its presence felt with an expected high of 20C. Rain will develop in the morning with heavy showers a possibility, but will clear in the afternoon."
On Friday things are a little better with isolated showers predicted for both cities combined with westerly winds.
"Saturday should see periods of rain, possibly heavy and thundery, and the westerly wind will do a complete turnaround and become northerly," Best said.
"Temperatures of 21C for Rotorua and 24C for Tauranga can be expected.
"Sunday will see showers and little wind."
The online forecast predicts rain with light winds on Monday, showers with light winds on Tuesday and rain with northerlies on Wednesday.
"The forecast up until Sunday has been compiled by a meteorologist after that is an automatic forecast which is not always accurate," Best said.
Rotorua forecast
Today: High 26C overnight 13C. Fine apart from some morning cloud. Westerly breezes developing.
Tomorrow: High 23C overnight 14C. Morning and evening cloud. Westerlies.
Thursday: High 20C overnight 12C. Rain developing morning, clearing afternoon. Northwesterlies.
Friday: High 23C overnight 13C. A few showers. Westerlies.
Saturday: High 21C overnight 13C. Periods of rain developing. Northwesterlies.
Sunday: High 21C overnight 13C. Showers with little wind.
Monday: High 21C overnight 11C. Rain with light winds.
Tuesday: High 21C overnight 11C. Showers and light winds.
Tauranga
Today: High 27C overnight 16C. Fine apart from some morning cloud. Light winds and sea breezes.
Tomorrow: High 25C overnight 17C. Morning and evening cloud, otherwise fine. Westerlies.
Friday: High 24C overnight 16C. A few showers. Westerlies.
Saturday: High 24C overnight 15C. Periods of rain developing. Northwesterlies.
Sunday: High 23C overnight 15C. Showers with little wind.
Monday: High 22C overnight 14C. Rain with light winds.
Tuesday: High 22C overnight 14C. Showers light winds.
