(CNN)One of Arizona's largest wildfires has scorched more than 139,000 acres and continues to spread rapidly as weather conditions are expected to remain hot and dry.
More than 1,000 people are fighting to tame the Telegraph Fire, burning east of Phoenix, as it has grown and began merging with the neighboring Mescal Fire. Both fires have charred more than 210,000 acres.
The Telegraph Fire's containment fell to 59% from 68% Tuesday while the Mescal Fire is contained at 88%.
The communities of El Capitan, Dripping Springs and Beverly Hills were asked to evacuate Tuesday, according to the Telegraph Fire Information Facebook page.
The order was prompted after dry, windy conditions pushed smoke and flames through the area, eventually impacting state Route 77.
The Telegraph Fire is one of the 10 largest fires the Southwest has seen since 1990, according to CNN meteorologist Michael Guy.
And the weather in the coming days could make firefighters' jobs more difficult.
The areas surrounding the fire are under excessive heat warnings -- until the heat wave gripping the West eases over the weekend, Guy predicts. There is also the possibility of dry thunderstorms, which can produce strong wind gusts and lightning with little beneficial rain. If those pop up, they have the potential to spread existing wildfire flames or ignite new fires by lighting strikes, Guy said.
Incident commander Dave Bales said Tuesday night that the biggest spread in the previous 24 hours has been around the community of El Capitan, which was evacuated Monday.
"That's been some intense firefighting," Bales said.
The fire ignited June 4 about 100 miles east of Phoenix. The cause is under investigation.