Honestly, if you stepped outside in Yorba Linda this morning, you probably noticed it felt a little... different. Not exactly "winter in California" vibes.
While the official temperature in Yorba Linda today is sitting at a comfortable 72°F right now, there is a weirdly dry crispness in the air that makes it feel much warmer. We are looking at a high of 78°F before the sun dips. That’s nearly ten degrees above the typical January average of 68°F.
It’s sunny. Like, aggressively sunny.
The Weird Science of Yorba Linda’s Heat
Most people think "Southern California weather" is just one big sunny blob. It isn't. Yorba Linda sits in this unique pocket where the Santa Ana River Canyon acts as a giant funnel for air moving from the high desert down to the coast. Basically, as air drops from the Great Basin—which is over 4,000 feet up—it compresses.
Physics is a trip. For every 1,000 feet that air drops, it heats up by about 5°F.
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By the time that desert air hits the "Land of Gracious Living," it’s bone-dry and toastier than it started. Today, the humidity is hovering at a measly 20%. When the air is that dry, your sweat evaporates instantly. You don't feel "hot and sticky"—you just feel like you're slowly turning into a piece of human jerky.
Why today isn't a "typical" January day
If we look at the historical data from sites like WeatherSpark or Time and Date, a normal January 18th in Yorba Linda should be around 68°F with a low of 47°F. Today’s low of 52°F and high of 78°F means we are definitely leaning into an "unseasonable" territory.
- Current Temp: 72°F
- Today's High: 78°F
- Humidity: 20% (Dry!)
- Wind: 3 mph from the East
The wind is currently a lazy 3 mph coming from the east, but don't let that fool you. That easterly direction is the classic tell-tale sign of a weak Santa Ana influence. Even a light breeze from the desert keeps the marine layer—that cool, misty "May Gray" stuff—pushed way out to sea.
Is this a "Heat Wave" or Just Winter?
In Yorba Linda, we don't really get traditional winters. We get "Green Season" and "Brown Season." Right now, we should be in the green, rainy phase, but with a 10% chance of precipitation today, nobody is holding their breath for a downpour.
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The UV index is low (around 1), so you won't fry in ten minutes, but the combination of 78°F and 20% humidity is the perfect recipe for dehydration. You've probably noticed your skin feeling tighter or your throat a bit scratchy. That's not a cold; it's just the desert air doing its thing.
Experts at the Scripps Institution of Oceanography have been studying how these winter warm spells are changing. Interestingly, while the "big" Santa Ana wind events might be getting slightly less frequent due to shifting high-pressure systems in the Great Basin, the temperatures during these events are actually trending higher.
Basically, when it gets warm in January now, it gets really warm.
What You Should Actually Do Today
Since the temperature in Yorba Linda today is peaking at 78°F, your usual "winter" routine is probably out the window.
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Skip the heavy layers. A light hoodie is fine for the morning, but by 2:00 PM, you’re going to want a t-shirt. Because the air is so dry, you need to drink about 20% more water than you think you need.
If you're heading to Carbon Canyon Regional Park or hitting the trails near Chino Hills State Park, be careful. The vegetation is still recovery-mode dry. Even though it's "only" 78°F, the low humidity makes fire risk a real thing in the foothills.
Tonight, the temperature will plummet back down to 52°F. That’s a 26-degree swing. It’s a classic valley phenomenon—clear skies allow all that daytime heat to radiate straight back into space the second the sun goes down.
Check your hydration levels now. If you're planning an outdoor workout, aim for late afternoon when the sun is lower but the air is still warm. Keep an eye on the easterly winds; if they pick up, the humidity will drop even further.
Stay cool, stay hydrated, and enjoy the "winter" sun while it lasts.