Fullerton is basically ignoring the calendar right now. If you stepped outside this morning near Harbor Boulevard, you probably felt it—that dry, oddly warm breeze that makes it feel more like May than mid-January. While the rest of the country is shivering through actual winter, the fullerton 10 day forecast is serving up a "winter heat wave" that has everyone trading their hoodies for t-shirts.
Honestly, it’s a bit jarring. We just came off a massive December drenching that finally pulled California out of a 25-year drought. Now? We're looking at temperatures hitting the 80s.
What the Fullerton 10 Day Forecast Really Looks Like
If you’re planning your week, don't expect a sudden return to rain. The ridge of high pressure sitting over the West Coast is holding strong. This isn't just a "nice day" fluke; it's a sustained pattern driven by some pretty intense Santa Ana winds.
The Immediate Outlook
Today and tomorrow are the peak. We’re looking at a high of 81°F today, Tuesday, and it’s staying exactly there through Wednesday. The nights are still crisp—dropping down to about 48°F—which is classic Southern California. You’ll be sweating at 2:00 PM and reaching for a blanket by 10:00 PM.
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By Friday, January 16, things "cool down" to 78°F. I say that with quotes because 78 is still nearly 10 degrees above the historical average for this time of year. If you have outdoor plans for the weekend, Saturday and Sunday (January 17-18) are looking beautiful with highs hovering around 78-79°F.
The Shift Next Week
The real change starts hitting around Monday, January 19. We finally see the mercury slide back toward the low 70s. By the time we get to Thursday, January 22, the fullerton 10 day forecast suggests we might actually see some clouds and a high of only 67°F. There’s even a 15-20% chance of rain toward the end of next week, but don’t wash your car just yet—it’s looking pretty localized.
Why It’s 80 Degrees in January
It feels wrong, right? National Weather Service meteorologist Brian Lewis noted that these numbers are pushing record territory. The primary culprit is the Santa Ana wind system. Usually, these winds bring a massive fire risk because they’re hot and bone-dry.
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However, there’s a silver lining this year.
Because we had such a wet December—one of the wettest on record—the hills around the Fullerton Loop and Laguna Lake are actually green and holding moisture. The plants aren't "tinder-dry" yet. So, while it’s windy and hot, we aren't under the same red-flag stress we’d normally be in during a dry year.
Breaking Down the Daily Numbers
- Mid-Week Peak: Tuesday and Wednesday are the hottest at 81°F. UV index is around a 3, so you can still get a burn if you're out at Hillcrest Park for too long.
- The Weekend Buffer: Expect 78°F to 79°F through Sunday. It’s perfect "outdoor dining" weather.
- The Cool Down: Monday starts the descent. We go from 75°F on Monday to a much more "January-like" 67°F by next Thursday.
- Humidity Levels: It’s dry. We’re talking 18% to 30% humidity for the next few days. Your skin is probably going to feel it.
The Weird Connection to the Drought
It’s impossible to talk about the weather in Fullerton right now without mentioning the drought. For the first time in two and a half decades, the U.S. Drought Monitor shows California is 100% drought-free.
That’s wild.
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But even with the fullerton 10 day forecast looking like a summer vacation, water experts are still nervous. Why? Because the Sierra Nevada snowpack—which provides about a third of our water—is only at 70% of its normal level. We’re getting rain and heat in the valleys, but we aren't getting enough snow in the mountains. If this heat wave lasts too long, it could start melting what little snow we actually have.
How to Handle the "Winter" Heat
If you're living through this 10-day stretch, you've gotta adapt.
- Hydrate the Plants: Even though we’re out of the drought, three or four days of 80-degree weather with 18% humidity will suck the life out of your garden. Give your sensitive plants a deep soak in the evening.
- Layers are Mandatory: The 30-degree swing between the daily high and the nightly low is brutal on the sinuses. Keep a light jacket in the car even if it feels like summer when you leave the house.
- Check the Winds: Santa Anas can be unpredictable. If you're driving a high-profile vehicle on the 57 or the 91, keep both hands on the wheel. Gusts can hit 30+ mph even when the sky is perfectly blue.
What to Expect Long-Term
Looking past the next 10 days, the pattern might finally break. Most long-range models suggest a return to a more "active" (read: rainy) pattern toward the end of the month. For now, enjoy the sun. Go hit the trails at the Fullerton Arboretum or grab a coffee in Downtown Fullerton.
The heat is temporary, but the dry air is definitely here for the week. Stay hydrated, keep an eye on those dropping temperatures after sunset, and maybe keep the umbrella nearby for next Thursday—just in case that 20% chance of rain actually decides to show up.
Next Steps for You
Check your outdoor irrigation timers today. With temperatures hitting 81°F, your lawn will need a bit more water than it did last week, but don't overdo it—we want to keep that "drought-free" status as long as possible. If you're planning a hike at Craig Regional Park, aim for before 10:00 AM or after 4:00 PM to avoid the direct overhead sun.