Honestly, if you're looking at the extended San Diego forecast right now, you might be a little confused. One minute you're seeing headlines about a "weak La Niña" bringing dry spells, and the next, your phone is buzzing with a 40% chance of showers for the weekend. It's classic San Diego. We live in a land of microclimates where it can be 75°F in La Jolla and a crisp 62°F in Escondido at the exact same time.
But let’s get into the weeds of January 2026. Usually, this is our "coldest" month—which, let’s be real, just means we finally put on a Patagonia vest over our flip-flops. This year, though, the patterns are doing something a bit funky. We're seeing a weird tug-of-war between high-pressure ridges keeping us dry and sudden "subtropical influences" that might dump more rain than the averages suggest.
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What the Models Are Actually Saying
Right now, the National Weather Service is tracking a ridge that's basically acting like a giant umbrella over Southern California. This is typical for the weak La Niña we’ve been hearing about all winter. It blocks the big, juicy storms from the North Pacific. However, the latest ensemble models—basically a bunch of computer simulations trying to agree on something—are starting to show a break in that ridge toward the end of next week.
If that happens? We get "whiplash weather."
We’re talking about a transition from sunny, 73°F days to "radiational cooling" nights where inland valleys like Poway or Santee might actually see some patchy frost. It’s a wild swing. One day you're at Balboa Park thinking it's basically summer, and twelve hours later, you're scraping ice off a windshield.
The Reality of the Extended San Diego Forecast
Most people check a 10-day forecast and take it as gospel. Don’t do that here. In San Diego, the "marine layer" is the ultimate wildcard. Even if the extended San Diego forecast calls for clear skies, a shift in onshore flow can bring in that "May Gray" energy months early, trapping cool air at the coast while the inland folks bake.
Temperature Breakdown: Coastal vs. Inland
If you're planning a visit or just trying to figure out if you can finally turn off the AC, here is how the numbers are actually shaking out for the rest of the month:
- The Coastal Strip (Mission Beach, Del Mar): Highs are hovering around 65°F to 68°F. It’s steady. It’s reliable. But the humidity is higher, so 65°F feels a lot damper and "chillier" than you’d expect.
- The Inland Valleys (El Cajon, Escondido): This is where the drama is. Highs can hit 76°F tomorrow, then plummet to 52°F by the weekend if a trough moves in.
- The Mountains (Julian): If you're looking for snow, you might be waiting a while. The current long-range outlook favors warmer-than-average temps for the mountains, meaning any precipitation we do get will likely be a cold, miserable rain rather than a winter wonderland.
Is the "Dry Winter" a Myth?
We were told La Niña means a dry year. But 2026 is proving that climate rules are more like suggestions. We’ve already seen a few "weak waves" moving up from the south that the models didn't catch until 48 hours out. Meteorologist Brian Lewis from the NWS recently pointed out that these subtropical influences can override the "dry" La Niña signal. Basically, don't leave your umbrella in the garage just because the seasonal outlook said "below-average rainfall."
Why the Jet Stream is Acting Up
There is some technical stuff happening way up in the atmosphere that affects your weekend plans at the Zoo. The jet stream—that river of air that steers storms—is currently "negatively tilted." This is weather-speak for "it’s being blocked."
When the jet stream gets blocked, we get these long stretches of beautiful, dry Santa Ana conditions. The air gets super dry, the visibility is insane (you can see the Coronado Islands perfectly), and the fire risk goes up. But when that block finally snaps? It usually snaps hard. That’s why the extended San Diego forecast for the final week of January is looking increasingly "unsettled."
Travel Tips for the "San Diego Winter"
If you’re coming from the Midwest, you’re going to laugh at us. You’ll be in the pool while we’re in parkas. But for locals and savvy travelers, the next two weeks require a specific strategy.
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- The 3-Layer Rule: You need a base shirt, a light sweater, and a windproof shell. The temperature drop at sunset is aggressive. It can go from "perfect" to "shivering" in thirty minutes.
- Surf Watch: While the weather stays dry, the swells are actually picking up. Winter is prime time for Black’s Beach and Sunset Cliffs, even if the air is chilly.
- Inland Frost: If you have sensitive plants in places like Ramona, keep an eye on those "clear sky" nights. Without cloud cover to trap the heat, the ground temp can drop fast.
The Long View: Heading into February
Looking further out, the Climate Prediction Center is betting on a transition to "ENSO-neutral" by early spring. What does that mean for you? It means the weather is going to get even more unpredictable. Neutral years are like a box of chocolates—you never know if you're getting a month-long drought or an atmospheric river that floods Fashion Valley.
For now, expect the "warm and dry" trend to dominate the next 7 days, with a significant shift toward "cool and damp" as we hit the tail end of the month.
Actionable Next Steps
Check the "Area Forecast Discussion" from the San Diego NWS office if you want the real story behind the icons on your weather app. They update it a few times a day, and it's where the actual experts talk about their "forecast confidence." If they say confidence is low, take that 10-day forecast with a massive grain of salt. Also, if you’re heading inland, keep an eye on the wind alerts—Santa Anas can make driving a high-profile vehicle on the I-8 a total nightmare.