In Borrego, the low thermometer reading for Aug. 17 was 85 degrees, equaling the date's previous milestone for high minimum temperature, set in 2001, according to the National Weather Service.
On Sunday, a stifling 107-degree high in Campo topped by one degree the previous record set in 1962, and a high of 103 degrees in Ramona was 4 degrees up from the prior record, set three years ago. Highs of 102 in Alpine, Escondido and El Cajon, meanwhile, broke records set in 1992.
The slow cooling trend enjoyed by most of the region will continue into next weekend, the weather service reported, with temperatures moderating between 10 and 15 degrees.
Despite the more comfortable climate, meteorologists advised residents to continue taking precautions against dehydration, heat stroke and other high-temperature-related ailments as the summer goes on. Seniors, young children and pets lacking adequate shelter are most susceptible and must never be left in parked cars, which can quickly become death traps on hot days, the agency advised.
During such balmy weather, people should try to limit their outdoor activities; wear lightweight and loose-fitting clothing; drink plenty of water while avoiding sugary and alcoholic beverages; take frequent breaks in shaded or air conditioned areas; and heed any signs of heat exhaustion.