He's even seen some fires grow larger than a million acres in size.
"But topography plays a huge part in wild fire expansion," he says. "A wild land fire can run uphill nine times faster than it can on the flat."
Some fires can even influence the weather.
"What happens is you get this huge amount of fuel burning - from the trees themselves and the forest products that are there - and you get this great intensity of heat," Fred explains. The heat rises as the fire intensifies, and when it reaches the higher atmosphere it can pull down the jet stream.
Fred says the effect can be drastic. Sometimes, thunderstorms and lightning will develop in the wake of a large fire.
"A lot of people believe that all fires create their own weather, but that's not actually quite correct," Fred says.
''It takes a certain amount of fuel ... and then you have to combine that with the weather ... and the relative humidity and wind speed."