It is looking like a total curveball for January. Honestly, if you were expecting the usual damp, gray South Bay winter morning for Tuesday, January 13, 2026, you’re in for a massive shock. We’re basically skipping the rest of winter for a day. While the rest of the country might be shivering, weather tomorrow in San Jose California is going to feel more like a preview of late April than the middle of the rainy season.
The National Weather Service has been tracking a significant ridge of high pressure parked over the Eastern Pacific. This isn't just a minor blip. It’s a full-on "warm-up" that is sending temperatures roughly 5 to 10 degrees above what we’d normally see this time of year. If you have been living in the valley for a while, you know that 65°F in January isn't unheard of, but the way it’s arriving—bone-dry and crystal clear—is definitely going to change how people plan their day.
What the Numbers Actually Look Like
Let’s get into the weeds of the forecast because the timing of these temperature swings matters more than the peak high.
Tuesday is going to start off crisp. Really crisp. We are looking at an early morning low of about 41°F around 6:00 AM. If you’re heading out to work or taking the kids to school, you’ll still need that heavy coat. But here is the kicker: as soon as the sun clears the Diablo Range, things move fast. By noon, we’ll be hitting the mid-60s.
- Morning (7 AM - 10 AM): Hovering between 42°F and 52°F. Clear skies mean the sun will feel stronger than the air temperature suggests.
- Afternoon Peak (1 PM - 4 PM): The high will settle around 65°F or 66°F. It’s perfect "t-shirt and a light hoodie" weather.
- Evening (6 PM onwards): Temperatures drop quickly once the sun sets. Expect a dip back into the 40s by late evening.
There is zero chance of rain. Literally 0%. After a somewhat wet start to the month—we already saw over 3.6 inches of rain earlier this January—this dry spell is a welcome break for anyone tired of mud and gray skies. Humidity is going to be sitting around 43% in the afternoon, which is pretty dry for a coastal-adjacent valley. It basically means no "sticky" feeling, just that classic, clean California air.
The Microclimate Factor: Why Your Neighborhood Might Differ
San Jose is famous for its microclimates, and Tuesday’s weather tomorrow in San Jose California will highlight that. If you are down in Almaden Valley, you might feel a couple of degrees warmer because of the way the hills trap heat. Conversely, if you’re closer to the San Francisco Bay near Alviso, expect a slightly more consistent breeze that might keep the "perceived" temperature a little lower.
The wind is going to be "light and variable," according to the latest NWS Bay Area discussion. We’re talking 3 to 5 mph. That is barely enough to rustle the leaves on the palm trees. For pilots flying out of Mineta San José International (SJC), it’s a dream scenario—VFR (Visual Flight Rules) conditions all day long. For the rest of us, it just means no wind chill to worry about.
Is This Part of a Larger Trend?
Some local weather watchers are pointing to the "radiational cooling" we’ve been seeing at night. Because there are no clouds to act as a blanket, all the heat the ground absorbs during the day just vents straight into space at night. That is why we have these massive 25-degree swings between lunch and bedtime. It’s a very "desert-like" behavior for a Mediterranean climate.
Expert meteorologists at the Monterey office have noted that while this ridge is keeping us dry, it’s also creating a bit of a stagnant air mass. You might notice a slight haze on the horizon toward the Santa Cruz mountains. It’s not necessarily smoke or heavy smog, just the result of a lack of onshore flow to "scrub" the valley floor.
Planning Your Tuesday in the South Bay
Since the weather is going to be so cooperative, it’s a crime to stay indoors. If you’re a remote worker, this is the day to take your laptop to San Pedro Square Market or a patio in Willow Glen. The Wildcat Mountain Ramblers are actually playing over at Sam's Bar-B-Que tomorrow evening starting around 6:00 PM. While it’ll be cooling down by then, the dry air makes it much more tolerable than a damp night.
Pro-tip for commuters: The sun is setting at 5:12 PM. Because the air is so clear, the "Golden Hour" is going to be particularly intense. If you’re driving west on I-280 or Highway 85 during the evening rush, keep those sunglasses handy. The glare off the asphalt when the sky is this clear in January can be brutal.
Ultraviolet Risks and Skin Care
It sounds weird to talk about sun protection in the middle of winter, but the UV index tomorrow is expected to be a "Moderate" 3. It’s not summer-level intensity, but if you’re planning a midday hike at Mission Peak or Alum Rock Park, you’ll be under direct exposure for hours. The lack of cloud cover means there’s nothing filtering those rays. A bit of SPF 30 isn't a bad idea if you're going to be out for the full afternoon.
Looking Beyond Tomorrow
This dry, warm pattern isn't just a one-day wonder. The long-term models show this ridge holding steady through Thursday and Friday, with highs potentially creeping even higher toward 69°F by the weekend. We are in a "blocked" pattern where the storm tracks are being pushed way up into the Pacific Northwest and Canada.
While it’s great for outdoor dining and soccer practice, the "above normal precipitation" outlook for the end of the month suggests we shouldn't get too comfortable. This is a classic California winter "intermission."
Actionable Steps for San Jose Residents
- Layering is Mandatory: Don't let the 65°F high fool you. You need a heavy outer layer for the 41°F morning and a light layer for the afternoon.
- Hydrate Your Garden: Since we’ve had a dry week and tomorrow will be low humidity, check your potted plants. They dry out faster in this "warm ridge" weather than you’d think.
- Check Tire Pressure: Rapid shifts from 40-degree nights to 65-degree days can sometimes trigger your TPMS light. It’s just physics—don't panic, just check the air.
- Plan Outdoor Maintenance: If you’ve been putting off cleaning the gutters or fixing a fence post from the last storm, Tuesday through Thursday is your optimal window before the next cycle of weather potentially shifts back to wet.
The weather tomorrow in San Jose California is effectively a "get out of jail free" card from the standard winter gloom. Take advantage of it. Whether that means a walk through Santana Row or just eating lunch outside, these clear, still days are exactly why people pay the "sunshine tax" to live in the Santa Clara Valley. Keep an eye on the evening temperatures, though, as that 20-degree drop happens faster than most people expect once the sun hits the horizon.
Check the local sensors at SJC or the various backyard stations in the West Valley if you want hyper-local updates, but for most of us, "Sunny and 65" is the only headline you need to remember. Enjoy the warmth while it lasts. Winter isn't done with us yet, but for tomorrow, it's definitely taking a break.