But the NSW Rural Fire Service Deputy Commissioner, Rob Rogers, said a barbecue on the first day of 2013 can still be fired up as long as precautions and sensible behaviour prevail.

''We are not saying people can't enjoy themselves on New Year's Day, we want people to enjoy responsibly. People have to remember it only takes one spark to cause devastations and no one wants to be responsible for that,'' he said.

A gas or electric barbecue is allowed if it is on a residential property within 20 metres of a house or dwelling or in a picnic area approved by a council, national parks or state forest agency, he said.

An ''immediate and continuous supply'' of water must be available as well, while a ''responsible adult'' is to be in charge of the barbecue.

Mr Rogers said the RFS has been in consultation with the Bureau of Meteorology, which has predicted high temperatures and windy conditions on Tuesday.

''In a large part of NSW, it's going to be warm. We're talking 39 degrees and strong winds and that pattern is the thing we're expecting to see. This is why there is a ban.''

A total fire ban means a ban on any fires in the open, he said. The bans cover greater Sydney, including the Blue Mountains, Gosford, Hawkesbury and Wyong. They also cover Illawarra/Shoalhaven, the greater Hunter, lower central wester plains, central ranges and southern ranges.

The Bureau of Meteorology advises that the greater Hunter, lower central western plains, central ranges and southern ranges will have a very high fire-danger rating.

''It's not the biggest ban but considering it's New Year's Day it's significant,'' Mr Rogers said.

''This is not the worse we've seen conditions in NSW and not the most amount of areas but a fair amount of the state is covered by the ban. This summer we've had a few fires early on, then came the rainy period but we are coming out of that.''

Mr Rogers said the fire service chose the 5am start for the ban rather than midnight to accommodate for campers and the traditional fireworks celebrations.