Firefighters responded quickly after being alerted to reports of smoke in the Berry Jerry National Park, about 30 kilometres west of the city, early on Friday morning.

Upon arrival, Collingullie and Glenfield rural fire brigades found grass and an old river red gum tree alight.

Riverina Rural Fire Service operational officer Bradley Stewart said all indications of the fire's cause pointed towards campers not extinguishing their campfire.

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Fortunately, Mr Stewart said Friday's conditions were "relatively benign" considering the season and firefighters managed to get on top of the fire quickly.

However, campfires in national parks are only allowed when there is a purpose-built, designated area and to his knowledge there is no campground at this particular national park.

"The campfire would fall into that grey area of not being legal," he said. "It is an offense to leave a fire unattended and the penalty for doing so is a $1100 fine."

People only need to look to Queensland's bushfire-ravaged K'Gari-Fraser Island to see the devastation a fire could cause. The fire, which burnt almost half the island, was sparked by an illegal campfire in mid-October.

NSW RFS operational officer Angela Burford said the bushfire danger period is "well and truly" under way and, although firefighters are not expecting a "devastating season," it is not the time to be complacent.

"Campfires can become problematic quite quickly, particularly in a relaxed environment. People are quite jovial and having a few drinks and that's when you are not being conscious and keeping an eye on it," she said.

"We have to be very careful of the fuel loads around it. If there is grass next to a campfire all it takes is a little ember to fly over and start a grass fire and if that fuel is dry it could catch alight and run quite quickly.

"We need people to enjoy the Christmas and summer period, which is what we deserve after the year we have been through, but still keeping in mind to be quite vigilant around fire.

"Be mindful of what we went through last year. We don't want to go through that devastation again."

Campers should keep an eye on fires until they are fully extinguished and ensure a water source is nearby.