Print San Diego County’s Borrego Springs, the westernmost part of the Sonoran Desert, experienced the hottest June on record with an average monthly temperature of 91.7 degrees, according to the National Weather Service. That broke the previous hottest average for June of 90.9, set in 1981. “There was lots of high pressure that caused multiple heat waves in June,” said Brandt Maxwell, a forecaster at the weather service office in Rancho Bernardo. “And there’s going to be more high temperatures out there this weekend.” The weather service says Borrego Springs and Ocotillo Wells could reach the 117 to 118 degree range on Saturday, and 116 on Sunday. An excess heat warning will be in place for the eastern reaches of the county from 9 a.m. on Saturday to 10 p.m. on Sunday.