So, you're looking at the san luis az weather forecast and thinking it’s just another predictable desert week. Honestly, I get it. We’re tucked right into that southwest corner of Arizona where the sun basically lives year-round. But if you’re planning a weekend trip or just trying to figure out if you need a jacket for your morning commute across the border, there’s some nuance here that the basic apps usually gloss over.
Right now, as we sit in mid-January 2026, San Luis is doing that classic desert "double-cross."
The Current Vibe in San Luis
As of tonight, Saturday, January 17, it’s a crisp 61°F. That sounds comfortable until you realize the humidity is sitting at a bone-dry 19%. With a 7 mph wind coming out of the north, that 61 degrees feels a lot sharper than it would in, say, Florida. It’s clear skies for the moment, but don’t let the "nighttime clear" status fool you into thinking tomorrow will be a carbon copy.
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The Breakdown: Today and Tomorrow
Today specifically, we’re topping out at a high of 77°F. That’s peak "t-shirt and shades" weather. But the real story is the wind. It’s kicking up to 13 mph from the north today. If you're out near the Port of Entry or walking around the neighborhoods, that's enough of a breeze to make the dust dance.
Tonight, the low hits 52°F. It’ll be clear but we’re expecting some periodic clouds to roll in.
Sunday, January 18, brings a slight shift. We’re looking at:
- High: 76°F
- Low: 50°F
- Sky: Partly sunny during the day, turning mostly cloudy by night.
- Rain? There’s a tiny 5% to 10% chance of precipitation.
Is it going to pour? Probably not. But in a place where we measure annual rainfall in single digits, even a 10% chance is worth a glance at the sky.
Why the Next 10 Days Matter
The upcoming san luis az weather forecast shows a remarkably stable temperature band, but the "feel" is going to change. Monday and Tuesday (January 19-20) keep us right around 76°F to 77°F.
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Wait, here's the kicker.
By Friday, January 23, we see a dip. The high drops to 72°F, and the humidity jumps up to 31%. Now, for most of the country, 31% humidity is nothing. For us? That’s a noticeable shift in the air quality. The wind also flips, starting to come from the southeast rather than the north.
Understanding the "San Luis Microclimate"
A lot of people check the Yuma forecast and assume it’s identical. It's close, sure. But being further south and closer to the Colorado River delta changes the wind patterns. Historically, January in San Luis sees highs around 71°F and lows near 45°F. We are currently running a few degrees warmer than the historical average, which tracks with the broader trends we've seen over the last few years.
If you’re working outdoors or heading to the San Luis Youth Center (keep in mind they’re currently closed for flooring until the 23rd!), you have to account for the UV index. Even in January, the UV index is hitting a 3. It’s not summer-level "melt your skin" sun, but it’s enough to catch a burn if you’re out at the parks all afternoon.
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Planning for the Week Ahead
If you're looking at the long-range view for late January, Saturday the 24th and Sunday the 25th are looking gorgeous—74°F to 77°F with clear to partly sunny skies. However, the humidity is expected to climb to 42% next weekend.
Basically, it’s going to feel "heavier" than the dry heat we’re having today.
Actionable Prep for San Luis Residents
- Layering is non-negotiable: When the gap between the high and low is 25 degrees (like the 77/52 split today), you will be freezing at 7:00 AM and sweating by 2:00 PM.
- Hydration overestimation: With humidity as low as 15% (today's projected low), you lose moisture through breathing faster than you realize. Drink more water than you think you need.
- Wind Awareness: North winds at 13 mph can be annoying for high-profile vehicles on the 95. Keep a firm grip on the wheel if you’re heading north toward Yuma.
- Sun Protection: Don't ignore that UV index of 3. If you’re at the border crossing for an extended period, wear a hat.
The san luis az weather forecast for the rest of the month is looking like prime "Chamber of Commerce" weather—mostly sunny, mild, and perfect for being outside. Just keep an eye on those overnight lows; they’ll sneak up on you once the sun dips behind the Gila Mountains.