A third wildfire started amid hot temperatures in steep terrain near the U.S.-Mexico border southeast of the Otay Open Space Preserve on Thursday.
Cal Fire San Diego said they were responding to the vegetation fire in Marron Valley south of Jamul Casino and State Route 94 at about 3:50 p.m.
The Border 7 Fire quickly grew to 90 acres but was not posing a threat to any structures. As of 8 p.m. Thursday, it was 10% contained.
The agency said the area was difficult to access by their firefighters.
Cal Fire crews were also battling another wildfire less than 20 miles north. The Skyline Fire had scorched about 100 acres before its forward rate of spread was stopped. The fire prompted evacuation orders for part of Lawson Valley, just east of Jamul, which remained in effect at 5 p.m.
Meanwhile, a fire started near the border of Santee and San Diego's Miramar neighborhood. The Miramar Fire had grown to 15 acres but crews had a handle on the blaze. It was about 50 percent contained by 4 p.m.
While there was no fire threat on the National Weather Service's threat index on Thursday, hot temperatures were still blaring down on San Diego County. A heat advisory expired at 7 p.m. on Wednesday.