Police are warning people to remain vigilant when opening windows overnight in an attempt to gain respite from the high temperatures.
MetService meteorologist Rob Kerr said temperatures were likely to reach 22 degrees Celsius throughout the night, rising to around 29 degrees Tuesday day-time and 30 degrees on Wednesday.
"It'll be a warm night tonight, with temperatures sitting around 22 degrees throughout," he said. "Looking into tomorrow, you may see a period of rain in the late afternoon and into the evening affecting the Hawke's Bay region, but the showers should largely hold off later in the week."
District Prevention Manager Inspector Dean Clifford said people should be cautious when attempting to cool their properties and cars, with burglars and thieves active.
"While keeping doors and windows open is great for staying cool, it can be of interest to those looking for easy and unwelcome access," he said.