MetService is predicting even higher temperatures - with 31C predicted for Alexandra - today as an anticyclone hovers over New Zealand.
"It's good news for the working week. The ridge is set to persist until Friday, which means a continuation of warm, settled weather," MetService meteorologist Ciaran Doolin said.
"Isolated showers are likely to continue to affect inland and higher-ground areas during the afternoons and evenings."
Sun should prevail across most of the country this week, apart from some rain in the far south — mainly Fiordland — today and tomorrow.
And it's not just the air that's warmer - Niwa meteorologist Ben Noll said that ocean temperatures around New Zealand have been, on average, 2C warmer than usual.
Temperatures across the country were in the mid-20s yesterday, with Auckland and Wellington reaching 24C and Dunedin hitting 26C.
The hottest spot was Hanmer Springs near Christchurch, where the thermometer hit 31C. Waiouru was the coolest with a high of 20C.
Baking hot temperatures sent more than 10 times as many people to popular beaches on the first weekend of summer as went last year.
In Otago Alexandra is expected to reach 31C today and again on Thursday.
Dunedin, Oamaru, Wanaka, Queenstown are all expected to reach the mid to high 20s today.
TOP TIPS TO STAYING COOL:
1. Stay hydrated throughout the day. Simple advice, but mum is always right - drink lots of water to ensure you stay hydrated.
2. Freeze. It might sound a bit quirky, but putting your sheets or pillow in the fridge is said to be very effective. Take them out when you're ready for bed and enjoy a cool sleep.
3. Keep the curtains, particularly in the bedroom, closed during the day. It will keep the sun out. Open the windows in the evening when the air is cooler.
4. Fill a hot-water bottle up with cold water instead and place it in the freezer. Place it under your feet or use it when you go to sleep. If it's too cold, cover it with a light cloth or hand towel.
5. Place a bowl of ice in front of an electric fan for even cooler air.
FOR PETS:
6. Take your pet to a groomer or vet for a haircut for the summer. Then they can enjoy exercise times rather than lying around trying to stay cool all day.
7. Frozen treats: Rubber chew toys that can be filled with treats can be frozen overnight for your fur friend. Make ice blocks by freezing a bowl of water with dog biscuits or other treats inside. The frozen goodies act not only as a treat but as an activity for your pet.
8. Take your pet for a swim. Simple and fun.
