Operations Commander for the NSW SES, Tony Day, said the Severe Weather Warning for damaging winds and surf will result from a deepening low over the Tasman Sea.

"This system is forecast to bring gusty winds to parts of the Mid North Coast and Hunter Regions on Tuesday, and powerful seas to the coast on Tuesday and Wednesday," Mr Day warned.

"The winds should average between 60 to 70 km/h with peak gusts in excess of 90 km/h over the coastal fringe and are expected to gradually ease during Wednesday."

Wind gusts of up to 25 km/h have been recorded in Kempsey, according to Weatherzone. Winds of up to 40 km/h are expected for Crescent Head and South West Rocks this afternoon.

A fallen tree has blocked the road in River Street near the hospital in West Kempsey.

Detours are in place and Essential Energy crews are investigating.

Mr Day said very heavy surf may lead to localised damage and coastal erosion along the coast.

"South and southeast facing parts of the coast are most at risk," he advised.

"Beach conditions in these areas could be dangerous and people should stay well away from the surf and surf exposed areas."

The Bureau of Meteorology weather warning issued at 11am today warned heavy surf may lead to coastal erosion between Narooma on the South Coast and Smokey Cape on the Mid North Coast.

A hazardous surf warning is also current along the entire NSW Coast. Surf conditions are expected to ease from Thursday.

"The most practical way the community can help is to avoid all not essential travel and to never drive, ride or walk through affected areas," Mr Day said.

The next Severe Weather Warning will be issued at 5.00pm today.