High pressure was forecast to strengthen and expand over the Desert Southwest Saturday through the middle of next week, bringing a heat wave to much of the region, the National Weather Service said.
The forecast calls for the system to bring in a prolonged heat wave and elevated fire weather conditions. The fire weather threat, while not critical, will be greatest Tuesday through at least Friday, the NWS said.
Gradual cooling and increasing humidity will help to ease conditions over the weekend and into next week.
A sea breeze and shallow marine layer was expected to keep temperatures moderated in the coastal areas, along with some patchy night and morning low clouds and fog at times, according to the NWS.
Get top local stories in San Diego delivered to you every morning. Sign up for NBC San Diego's News Headlines newsletter.
High temperatures in coastal areas Sunday were expected to be 69-74 degrees with overnight lows of 56-62, the NWS said. Western valley highs will be 81-86 and 89-94 in the foothills with overnight lows of 53-60.
Mountain highs were expected to be 88-98 with overnight lows of 55-65. Highs in the deserts will be 110-115 with overnight lows of 75-83.
Increasing temperatures and relative humidity of 10-15% were predicted to result in elevated fire weather conditions in the afternoons and evenings.
Northwest winds in the outer waters with a few gusts exceeding 20 knots were expected to continue each afternoon and evening Saturday through Monday.
An excessive heat warning was issued by the NWS from 10 a.m. Monday to 9 p.m. Friday for San Diego County deserts.
An excessive heat watch was issued from Tuesday morning through Friday evening for San Diego County mountains. And an excessive heat watch was issued from Tuesday morning through Thursday evening for San Diego County valleys.
The ridge over the Southwest was expected to slowly weaken late next week, with gradual cooling spreading slowly inland next weekend.
County Cool Zones
The county will open a Cool Zone site at the Borrego Springs Branch Library starting Monday, June 14 from 10 a.m. to 4 p.m. located at 2580 Country Club Road, Borrego Springs, CA 92004.
Regardless of vaccination status, anyone who enters a cool zone must wear a facial covering inside. This is in adherence to guidance from the California Department of Public Health.
More Cool Zone locations will be announced soon. To check, visit the county's website.
Beating the Heat
Residents can cool down with air conditioners or fans, and those who want to go outdoors during the heat wave are encouraged to wear sunscreen. Everyone should remember to drink plenty of water in order to stay hydrated.
Heat-related illnesses such as heat exhaustion, heatstroke and heat cramps pose a threat during these times, especially to vulnerable communities like the elderly and children.
The Centers for Disease Control said such illnesses can be identified by symptoms that include fatigue, headache, cramping, dizziness, nausea, or vomiting and fainting. Anyone who sees someone in distress is urged to call 911 immediately.
It is also encouraged to refrain from leaving children and pets unattended in cars in order to prevent tragedy. Temperatures in an enclosed vehicle can skyrocket within just minutes, causing serious injury or even death.
The San Diego Humane Society offered some tips to keep pets cool in hot weather. Like providing plenty of water at all times, including when away from home, leaving pets inside where it's cool at home as much as possible and not leaving a pet alone in a parked vehicle -- even with the windows open.
