NSW holiday-makers heading away for the long weekend have been urged to check fire danger conditions and be ready to flee if a bushfire sparks.

NSW RFS Commissioner Shane Fitzsimmons says travellers should have escape routes planned, and if the fire danger rating is severe, extreme or catastrophic, should postpone their trips.

There are about a dozen fires burning at an advice level across the state, and temperatures are forecast to soar into the 30s over the weekend.

"Fires can pose incredible danger for those not prepared or unaware of their surroundings, like those camping, on holidays or travelling in unfamiliar areas," he said in a statement.

He also urged campers to check if total fire bans have been declared in their area, and to take care when lighting cooking fires.