Frost fans are likely to be needed overnight due to falling temperatures in Hastings, threatening fresh buds.
The 2C forecast is for the ambient air temperature but many areas will fall to freezing.
Napier, closer to the heat-sink commonly known as the Pacific Ocean, will be just 1C warmer overnight.
MetService meteorologist Kyle Lee said Monday will largely be fine except for a few showers about the ranges during the morning and into the afternoon. The day's maximum will be about 13C.
He said southwesterly winds will be fresh about the coast at times.
Tuesday will be dry with the chilly southwesterly dying out during the day, bringing a warmer day's maximum temperature of 17C to Hawke's Bay.
Wednesday was "not looking too bad" as northwesterly winds returned.
"The eastern areas will be fine with high cloud and those northwesterlies will obviously keep the temperature relatively warm for the Hawke's Bay region - the temperature for Wednesday should be around 18C, perhaps even pushing higher on Thursday."
Sunrise on Thursday will be 6.15am but Bay sunshine will soon be a lot earlier, with daylight saving beginning Sunday, September 24 and running until April 1.
Mr Lee said like his fellow meteorologists he was keeping an eye on Hurricane Irma, moving towards Florida at a sustained 200km/h.
He said he was glad he was not in Florida "but I wish I was forecasting the system".
"A lot of us have a few links we have been checking to keep up to date on what is going on there," he said.
Media was "obviously hyping it up" but it was of "real significance".
He said it would be interesting to compare damage with the 2005 Hurricane Katrina.
That caused serious damage especially in New Orleans where there was loss of life and flood damage to 80 per cent of the city due to levee systems failing.
"We don't have anything like that in Florida but it is going to be pretty interesting to see what sustained wind they get when it reaches landfall."