Extreme heatwave incoming for the Hunter, bureau warns

Despite the southerly change on Monday and Tuesday, cooling things off after a hot weekend across the coast, the mercury will climb once again from today.

A Bureau of Meteorology spokesperson said on Tuesday afternoon the heatwave warning had been upped to extreme for the Hunter heading into Australia Day.

"We will experience really hot temperatures, plenty of those high 30s and into the 40s throughout the Hunter," they said.

The temperature is expected to hit 35 degrees in Raymond Terrace and 30 in Nelson Bay on Wednesday. and

Raymond Terrace maximums will be 40 and 41 degrees across both Thursday and Friday, before falling to 26 on Saturday.

Nelson Bay maximums will be a more moderate 33 and 36 on Thursday and Friday respectively and 26 on Saturday with a 70 per cent chance of rain.

The spokesperson said there is likely to be a southerly wind change very late on Friday afternoon into the early parts of Saturday pushing up the coast, bringing a cooler change.

"We will see a 13 degree drop from Friday into Saturday for maximum temperatures so it could be gusty, and we could see some storms with that southerly change."

The spokesperson said there was yet to be a Total Fire Ban released by the RFS but there was "certainly an increase in fire danger".

The State Emergency Operations Controller, Deputy Commissioner Peter Thurtell APM has urged people across NSW to look after their health as a wave of hot weather crosses the state this week.

"We know many people will want to head to the beach, a local swimming hole or swim in your backyard pool. Please be careful. Keep a watchful eye over children especially when they are near the water - all children need to be supervised," he said.

NSW Health has advised to avoid being outside in the hottest part of the day, stay hydrated, wear sunscreen and limit physical activity.