Mid-week a low pressure system will start to move from the country's northwest, meaning the first "real chance" of showers could be expected on Wednesday. High cloud is also set to increase, and the day could bring the highest temperature of 2018 so far of 26C.
Over Thursday and Friday the region could see some "very significant rain". This low pressure means any rain could fall in sudden bursts, and be accompanied by strong wind.
Showers in the ranges are expected to continue on Thursday when northeasterlies pick up, to cool down the day's high of 25C.
Rain will win out on Friday, with falls expected inland, and easterly winds. A high of 25C is expected.
"Hawke's Bay is looking pretty good for the next few days, with most of the weather affecting the country in the west," said Mr Adams.
"Things should begin improving as we go into the second week of 2018."
There will be plenty of outdoor events to make the most of the good weather while it lasts, from the New Years day Interislander Summer Festival Hawke's Bay Races at Hastings Racecourse, to Summer Sessions at Abbey Cellars.
There are also indoor activities to entertain the younger ones when the weather turns sour - like the Miniature World open workshop at Creative Arts Napier.
The week will be rounded out with the first events of the third annual Summer Cycling Carnival.