About 10 years ago my group entered through Nym in August and used and outfitter (name withheld) for canoes and a couple other things, including a burner.  The night before we looked it over and threw it in the pack. The outfitter said they expected a fire ban soon because of the lack of rain.  Our first night we realized the burner was broken and not usable.  Luckily we were able to cook over a fire for the entire week cuz there was no rain for the first 5 days of the trip.  Found out on exit that there was a fire ban established day after we entered.  It was very dry, and we were careful by choosing our campsites based on risk with a dry forest and cooking over the fire. 
I learned a couple things that trip... 1) always bring 2 burners or at least test your burner before you enter the park (man we felt stupid), and 2) cooking over a fire during a fire ban can be a necessary risk.