San Diego residents are in for a gentle ride as the region’s weather pattern shifts from a pleasantly cool weekend to a modest warm-up, with meteorologists hinting at the possible return of monsoonal moisture and thunderstorms later in the week. According to the National Weather Service San Diego, temperatures are set to rise from Monday, September 15, through Wednesday, September 17, 2025, with highs expected to climb 1 to 7 degrees above what’s typical for this time of year. For those who have grown accustomed to the city’s signature marine layer and cooler breezes, the weekend offers a final taste of fall-like conditions before the thermometer starts to inch upward.
“We have a few more fall-like days in our forecast before a big change in our weather pattern,” reported ABC 10News Weather Anchor Ava Kershner, echoing the broader consensus among local meteorologists. The weekend of September 13-14, 2025, promises “pleasant, cooler-than-average weather,” with marine layer clouds lingering along the coast and into nearby inland communities. These clouds are expected to slowly dissipate during the day, making way for mostly sunny skies—a welcome reprieve for anyone planning to spend Sunday by the ocean or in the city’s leafy neighborhoods.
Temperature-wise, Sunday, September 14, brings highs of 71 to 76 degrees Fahrenheit along the coast, 84 to 89 degrees inland, 79 to 86 degrees in the mountains, and a toasty 95 to 99 degrees in the deserts. Even the desert lows will cool down to the low 70s overnight, offering a brief respite from the relentless summer heat that often dominates the region’s weather narrative. The National Weather Service notes that the marine layer “will linger through Sunday morning, becoming shallower into midweek,” ensuring overnight low clouds continue to blanket the coast and adjacent valleys for at least a little while longer.
But change is on the horizon. Starting Monday, September 15, the mercury will begin a steady climb, and by Wednesday, most areas in San Diego County could see temperatures up to 7 degrees above average for mid-September. “Next week, we are tracking a warm-up with monsoonal moisture returning,” Kershner explained, highlighting a key shift in the region’s weather dynamics. The National Weather Service elaborates that by midweek, the marine layer will start to thin out, making way for warmer days and clearer skies—though not without a hint of uncertainty as to how the next act will unfold.
San Diego’s inland residents, who often bear the brunt of heat spikes, might be relieved to hear that the warming trend is expected to be modest rather than extreme. The forecast suggests a gentle transition, with daytime highs nudging above normal but not soaring into record-breaking territory. For coastal dwellers, the prospect of keeping windows open and enjoying the evening breeze remains very much alive, at least for the first half of the week. “It’s a soothing thought—the kind of forecast that suggests windows can stay open, raising the spirits of coastal dwellers and inlanders alike,” reported Hoodline, capturing the city’s collective sigh of relief.
Yet, as the week progresses, all eyes turn to the sky—and to the computer models that are, as Kershner notes, “having trouble agreeing what showers could look like next week.” The latter half of the week brings an element of unpredictability, as monsoonal moisture is poised to make a comeback. This atmospheric shift could introduce showers and thunderstorms, especially in the mountains and deserts, but there’s even the potential for some rain west of the mountains. “Our mountains and deserts will see thunderstorm chances pick up towards the end of the work week. We even have the potential to see a few showers west of the mountains around the same time!” Kershner added, encouraging viewers to stay tuned for updates as the forecast evolves.
According to the Area Forecast Discussion from the National Weather Service, “By the latter half of next week, however, the skies could become more animated as monsoonal moisture might return, bringing chances for a return of showers and thunderstorms, mainly to the mountains and deserts.” This brings a welcome note of excitement to the otherwise predictable September weather, as locals know that monsoonal flows can turn a sunny afternoon into a dramatic display of lightning and brief, intense downpours. However, the NWS cautions that the precise impact remains uncertain, as weather models diverge on the timing and intensity of any potential showers.
For those who track the weather not just as a casual interest but as a passion—or even a civic duty—San Diego’s Skywarn volunteer spotters remain ever vigilant. The National Weather Service confirmed that Skywarn activation is not currently requested, but the network of citizen-scientists is “on standby,” ready to report significant weather events that might slip past automated systems. Their dedication ensures that, should the weather take a sudden turn, local authorities and residents alike will have the information they need to stay safe.
These upcoming weather shifts are part and parcel of San Diego’s late-summer and early autumn climate. The region’s proximity to the Pacific Ocean and the influence of the marine layer often keep temperatures moderate, but the arrival of monsoonal moisture from the southeast can shake things up dramatically. Historically, these late-season monsoons have brought both relief from dry conditions and, occasionally, flash flooding—reminding residents that the city’s idyllic weather can still surprise.
Looking ahead, meteorologists urge San Diegans to keep an eye on the latest updates, as the interplay between lingering marine clouds and incoming monsoonal moisture could produce rapidly changing conditions. “Stay with the ABC 10News Pinpoint Weather Team for the latest updates,” advised Kershner, a sentiment echoed by her colleagues across local newsrooms. After all, in a city where weather is often the backdrop rather than the headline, even a minor warming trend or the chance of a thunderstorm can become the talk of the town.
As San Diego transitions from a cool, comfortable weekend into a week of rising temperatures and the possibility of dramatic skies, residents are reminded of the region’s unique climate—predictable, yes, but never dull. Whether you’re basking in the last days of coastal fog or hoping for the thrill of a late-summer thunderstorm, there’s no doubt that the coming week will have something for everyone, weather-wise. And as always, the city’s meteorologists and volunteer spotters will be watching the skies, ready to share whatever surprises nature has in store.
