PHOENIX -- The start of monsoon season is often marked by dry thunderstorms, lightning and wind with little or no rain.
That kind of weather can be very dangerous when it comes to wildfires.
With the dry winter and spring we've had, we could be looking at big trouble this summer.
Fire danger is especially high during the early summer months, but especially hot days bring that danger even higher.
Incident Meteorologist Valerie Meyers with the National Weather Service says that's because extreme heat can cause unpredictable fire behavior.
"When we can see extreme heat, I'm talking about when we're looking at records being broken, exceeding not just your normal summer day when we get up to 110, but when we start getting up to 115 to 120 degree range, it's a very, very strong rarefied atmosphere," says Meyers.
On June 29 of last year, Phoenix got to 119 degrees, making it our fourth hottest day on record. Within 36 hours, we saw the tragedy in Yarnell.
Nineteen firefighters were killed when a nearby thunderstorm pushed an outflow of wind through their area. They were trapped and overrun by flames.
The hottest day ever recorded in the Valley was in June of 1990 when the mercury reached 122 degrees.
That same day, six firefighters were killed fighting the Dude Fire near Payson.
Witnesses say a 30-foot wall of flames raced through the forest in one of the most unusual examples of fire behavior they'd ever seen.
Meyers says that's no coincidence and thinks we should learn from these tragedies by paying attention to the correlation between extreme heat and deadly fires.
"Just kind of a heads up, it can be extreme fire behavior it's really unpredictable. You really have no clue what's going to happen that day."