As the summer sun asserts its presence in San Diego, an Excessive Heat Watch has been declared for the upcoming Sunday and Monday, heralding temperatures that soar into the unforgiving mid-100s, according to the latest National Weather Service report. Residents of the Coachella Valley and San Diego County Deserts, as well as those traversing the San Gorgonio Pass near Banning, are advised to prepare for intense heat that could well persist into the following week.

Transition isn’t in the cards when it comes to the mercury’s rise, with San Diego's immediate forecast showing a steady climb. Today's high temperatures are expected to mirror Thursday's, around 5 degrees above normal for the lower deserts and roughly average elsewhere, while Sunday's scorcher is predicted to hit around 115 for the lower deserts, dragging the warmest inland valleys up to nearly 104 degrees as the marine layer continues to hold the coastal heat at bay for the time being.

Marine stratus—those low-hanging coastal clouds—will be a morning feature, reaching into the western valleys by sunrise and expected to clear by the afternoon, although they are likely to make a nightly cameo throughout the weekend, providing some respite from the heat as they creep in from the ocean.

Looking ahead, the National Weather Service anticipates that the strong high-pressure system currently parked over the eastern Pacific will shuffle eastward, potentially amping up the temperature gauge even further toward the week's end, high pressure's bullseye arguably shifting somewhere between the Great Basin and southwest states, the deterministic National Blend of Models (NBM) predicts Palm Springs seeing highs of at least 115 through next week, peaking Friday and Saturday with a 49 percent likelihood of surpassing that already staggering high.

Aviators and mariners catch a break as neither the sky above nor the waters off San Diego forecast trouble, aside from routine marine layer-induced visibility snags near coastal airports and gusty northwest winds for those navigating inland passes and canyons during the hottest times of the day. Authorities have deemed no significant marine conditions expected through Tuesday and skyward, clear visibility prevails except where those persistent low clouds squat during early mornings.

Despite the active, sweltering narrative the temperatures suggest, the National Weather Service urges everyday vigilance, not spectacle—with no Skywarn activation requested, spotters are nevertheless encouraged to report significant conditions as this dry, arid chapter unfolds.