Temperatures in some parts of East San Diego County topped 100 degrees by 10 a.m. Sunday, as a weekend heat wave gripped the southwestern United States.
In the Skye Valley community, it was 100 degrees as of 10 a.m. according to the National Weather Service.
El Cajon was expected to hit a record high of 102 Sunday, according to the National Weather Service. On Saturday, the city hit a new record of 94 degrees, said Larissa Johnson, a NWS meteorological technician.
The last time El Cajon hit 94 degrees on this date was in 2001, according to the NWS.
San Diego County high temperatures would range from the low 80s on the coasts to triple digits inland and in the deserts, according to the NWS.
It was 66 degrees at Mission Beach at 10 a.m.
While it's hot Sunday, Johnson said county residents can expect even higher temps Monday -- the first official day of summer -- because of an extreme high-pressure system passing over the Western United States.
The extreme heat began Saturday and a National Weather Service excessive heat warning was to remain in place until 8 p.m. Wednesday.
"The main message of our excessive heat watch is to get ready for the heat, particularly away from the coast Sunday through Tuesday," according to the NWS. "Temperatures will exceed 100 in most valleys and all deserts, even exceeding 115 in the lower deserts."
Daily high temperatures are predicted to range from 90 to 96 degrees in the mountains to 95 to 100 degrees in the valleys to 110 to 120 degrees in the deserts.
And the public was advised to avoid potentially serious heat-related ailments by staying well-hydrated, avoiding unnecessary outdoor labor and checking on neighbors and relatives -- especially those with health conditions and who lack air conditioning.
The heat was expected to break toward the middle of next week, according to the NWS.