Big swells and hazardous conditions are forecast for the Hunter coastline from Thursday due to a pressure system to the north.
Waves of up to four metres are expected from Thursday night and through the day on Friday, pushed by strong easterly winds.
The NSW Police Marine Area Command advises people to consider staying out of the water and avoiding surf-exposed areas.
"There will be hazardous surf and quite large waves which will hold a large amount of energy," BOM senior forecaster Jordan Notara said.
Mr Notara said the time period between waves was expected to be high, between 10 and 11 seconds, meaning conditions would be unpredictable for activities such as rock fishing.
"They may be in a situation where they do not think they're going to be washed off and a rogue wave could come," Mr Notara said.
The system is also expected to bring showers, before the surf conditions ease gradually into the weekend.
The system comes after a cool, dry April with the La Nina event over summer coming to an end.
Paterson (15.6C) and Cessnock (15C) both had their coldest April day on record on the 17th of the month and the long-term recording sites at Newcastle (15.9C) and Williamtown RAAF (15.5) had their coldest April day since 1966.
Overnight temperatures were also low across the Hunter for April.
Minimum temperatures were 2.6 degrees colder than the long term average in Lake Macquarie, two degrees cooler in Paterson, 1.2 degrees colder in Williamtown and 0.9 degrees chillier in Newcastle.
Newcastle recorded just 14.8mm of rain for the month of April - which was only 13 per cent of the long term monthly rainfall average of 115.5mm.
With no La Nina or El Nino in play, conditions are looking like they'll be closer to usual over the winter months in the Hunter.
According to the BOM's climate outlook, there is a 50 per cent chance of above average rainfall in Newcastle between June and August.
Winter daytime temperatures are predicted to be 0.6 degrees warmer than average, while overnight they're expected to be 1.2 degrees warmer.
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