"We've got temperatures up and until then in the lower 20s, then on Tuesday we see those temperatures dip for Napier and Hastings."
On Tuesday, maximum temperatures for Napier will drop to 18C and 17C for Hastings.
Waipukurau's high will only rise to 17C and Wairoa will be slightly warmer with a high of 19C.
The meteorologist said Wednesday would be a cooler day with temperatures dropping down to the mid-teens.
"Napier will reach about 16C as a maximum and Hastings will be about 15C which, especially for Hastings, is quite a bit lower than the average for this time of year," Makgabutlane said.
Waipukurau may only reach 14C and Wairoa just 13C on Wednesday. Overnight temperatures will teeter between 3C and 4C.
Makgabutlane said in some areas, especially sheltered places, there might even be some frost on Thursday morning - if there was a clear period overnight.
From Thursday, temperatures begin to rise and by the weekend most areas around Hawke's Bay will be back up to about 20C and be mainly fine and sunny.
Makgabutlane said after Tuesday's expected rainfall there wasn't much rain on the radar for the region for the following 10 days.