A National Weather Service heat advisory for the valleys is scheduled to remain in effect until 7 p.m. Tuesday, as high pressure and weak onshore flow continue to generate high heat in the region. Forecasters said high temperatures would be in the 80s along the coastline, in the 90s a few miles inland and over 100 degrees in the far inland valleys.
"Abnormally hot temperatures can be stressful to animals and humans, making it hard for the body to acclimate and remain hydrated,'' according to the weather service advisory. "Without precautions even healthy adults could experience heat stress and illness.''
Around 120 San Diego Unified School District schools without full air conditioning have implemented "minimum day schedules,'' including Clairemont, Crawford, La Jolla, Madison, Mira Mesa, Mission Bay and University City high schools, according to the district. After-school athletic activities have been canceled at all city schools.
A full list of schools is available on the district's website, sandi.net.
District officials said the forecast for Tuesday would be closely monitored, and a decision on whether to continue the shortened schedule would be made before noon.
Sweetwater Union High School District officials have implemented a minimum schedule at Mar Vista Academy, Castle Park and Hilltop middle schools, and Chula Vista, Mar Vista and Sweetwater high schools.
The heat wave also prompted San Diego Gas & Electric to ask its customers to lessen the strain on the electric grid by reducing their energy consumption between 11 a.m. and 6 p.m. SDG&E customers who participate in the "Reduce Your Use'' program could receive a bill credit for doing so, according to the utility.
Forecasters advised area residents planning outdoor activities to try to schedule them for early morning or evening, take frequent breaks in shady or air conditioned areas and to know the signs of heat exhaustion and heat stroke. Those headed outdoors were also advised to wear light, loose clothing and drink plenty of water.
Weather service forecasters said temperatures would cool Tuesday and Wednesday, but an "influx of monsoonal moisture from the south'' would cause humidity to rise.
San Diego County announced a public list of more than 100 “cool zones'' where county residents could beat the heat throughout the weekend and on Monday and Tuesday. The list included public spaces like libraries and shopping malls where people can escape the heat and get into some air conditioning.