Fox 5 viewers reported short, intense showers in Chula Vista, La Mesa, Santee, Lakeside, Ramona, Pine Valley and other parts of the East County mountains. People around the county reported hearing the rumble of thunder.
The National Weather Service issued a marine lightning warning, Fox 5 weathercaster Chrissy Russo said. More thunderstorms in the East County were possible in the afternoon, she said
Slightly cooler weather is expected in much of San Diego County Friday, but temperatures in the triple digits are again forecast for the deserts, Russo said.
High pressure over the Four Corners area of the western United States caused temperatures to soar in parts of San Diego County on Thursday. A record high of 107 degrees was reached, according to the National Weather Service.
A NWS heat advisory is scheduled to remain in effect until 9 p.m. for the deserts, where high temperatures of 106 to 112 are expected.
“The combination of a deeper marine layer from a coastal eddy, mid- and high cloud cover and an increase in low level moisture in the lower deserts will bring 5 to locally 10 degrees of cooling in most areas today,” according to the advisory.
However, weather service meteorologists said the decrease in temperatures in the deserts would be offset by increased humidity with little change or slightly higher heat index values. Peak heat index values of 108 to 114 are forecast.
Weather service forecasters said hot weather can be stressful for people and pets if precautions are not taken. Kids and pets must not be left unattended in vehicles because temperatures inside can quickly rise to lethal levels.
Strenuous outdoor activities should be rescheduled to early morning or evening hours, and those planning to spend time outdoors were advised to drink plenty of water and avoid alcoholic beverages.