Mr Hurley said stopping distances would be increased and some of the roads would be quite slippery.
MetService meteorologist Michael Martens told Hawke's Bay Today the rain had picked up at midday and most areas had experienced between 10mm and 20mm.
Some areas in the ranges had more than 30mm.
Overnight and this morning, 80-100mm of rain had been expected, especially about the eastern hills.
But instead, MetService Meteorologist Ciaran Doolin said in the last 24 hours a station in the Wairoa District had received 54mm of rain, with a peak intensity of 12mm at 8pm last night.
Hastings had 28.8mm, its peak intensity was 5.8mm at 10am this morning, Napier had 16.8mm, with most falling at 8pm at a recording of 4.6mm.
A station in central Hawke's Bay had 37.6mm, with most of the rain falling at 7pm last night with a measurement of 6mm.
The heaviest period of rain is expected to be at 2pm this afternoon for both Napier and Hastings.
A strong southwest is forecast for today which has prompted Metservice to advise residents to wear three layers of clothing as well as one wind-proof layer.
A high of 15C is forecast today in Napier with one degree lower expected in Hastings at 14C.
An overnight low of 5C is expected in both Napier and Hastings.
The rain is forecast to ease in the south through the afternoon before turning to showers everywhere in the evening, Mr Doolan said.
Hawke's Bay Civil Defence group manager Ian Macdonald said river levels were being monitored but with channels being low he expected there to be enough room for the forecast rain preventing any flooding.
Mr Macdonald said the rain had saved the region from potential "winter drought" and its arrival had been timed perfectly.