It's expected to be preceded by almost summery conditions, highlighted by Napier's forecast temperature range – a peak of 20C on Wednesday followed by a minimum 10C overnight - before the rain begins.
Fine temperatures are accompanied by fine weather at the start of the week as weather is mainly fine with some cloud throughout the region.
Federated Farmers Hawke's Bay president Jim Galloway said rain from a fortnight ago was running out quite fast and while it has helped to green up farms, significant amounts are needed.
He is hoping for more than 20mm of rain, ideally closer to 30mm.
There was little relief during the weekend past, with falls of just 4.6mm at Hawke's Bay Airport, 6.2mm at Mahia, and 6.6mm on the Takapau Plains, with none recorded at Hastings, said MetService meteorologist Andy Best.
It was much wetter in Wairoa which had 40mm.
It is not yet known how much rain there will be this coming week.
The drought was not over for farmers who have found the conditions mentally tough.
"They're up to about plan Z now, every few days farmers are having to reassess conditions," Galloway said.
The region south of Napier was heading for an eighth month in a row of well-below average rainfall, about 34 millimetres at the airport comparing with its June average of 77.4mm, Hastings' 38.2mm comparing with its June average of 82mm, and the 56mm on the Takapau Plains south of Waipukurau comparing with a June average of 85mm.
Mahia had 32.4mm which compares with a June average of 159.3 for the recording station.
Rainfall for the year is running at less than 50 per cent of average at all four stations.
