Yesterday's overnight frost sparked a spate of emergencies which included a fire in a vacant house and the bursting of hot water pipes and cylinders in homes.
The frost was the Bay's heaviest so far of this winter.
Emergency services were told squatters were believed to be sheltering in the house on Miller St because of the sub-zero temperatures when they got the reports of the fire at 6am. But no one was inside the badly damaged house.
It was the sixth call-out answered by Fire Service crews in the Hastings and Havelock North area in one-and-a half-hours before dawn. Included in the call outs were jobs for ruptured hotwater cylinders and pipes where the fittings had frozen.
Plumbers contacted by Hawke's Bay Today reported at least three other incidents where hotwater cylinders, pipes or fittings had ruptured.
Several similar incidents were reported after the last frost about July 12.
Fire Service Hastings senior station officer Mike Peachey said the Miller St house had no electricity supply and no other sources of ignition.
But the fire was well involved when the first of four appliances arrived following multiple calls from residents in the area.
Mr Peachey said the fire started towards the rear of the century-old villa and was being treated as suspicious. Police and Fire Service are investigating the incident.
The house was understood to have been unoccupied for several years, but it had been well maintained.
The first hot water cylinder incident attended by the brigade was in a mid-1900s home in Copeland Rd, Akina, about 4.30am, and the other at 5.50am caused flooding in a house in Diaz Pl, Flaxmere.
The Fire Service also received multiple calls to two rubbish fires, initially reported as a house fire and a garage fire respectively. The first was in Clive just before 6am, and the second several hours later on Napier's Hospital Hill.
The biggest frost was thought to have been -4.4C just south of Hastings, while frost was also evident in central and southern Hawke's Bay, with the Central Hawke's Bay District Council's official weather station recording temperatures plunging to -3.5C. In Dannevirke it was mildly warmer, at -3C.
The horticultural industry wouldn't have been particularly worried, according to Fruitgrowers Hawke's Bay president Leon Stallard, who said the timing was good.
"The more we have at this time of the year the better," he said.
"They kill the bugs, maybe there would be a bit of damage to very early stone fruit, but normally they'd be protected. This time of the year we expect some frost.
"In a month, in the spring, it might be different."