If you’ve lived in the Inland Empire for more than a week, you know the vibe. One morning you’re reaching for a light denim jacket because there’s a crisp, mountain-air chill rolling off Mt. Baldy. By 2:00 PM, you’re regretting every life choice as the mercury hits 98 degrees and the air feels like a literal blow-dryer. Weather for Upland California isn't just "sunny with a chance of more sun." It’s a complex, micro-climate-heavy experience shaped by the towering San Gabriel Mountains and the notorious Santa Ana winds.
Honestly, people from out of state think all of Southern California is just palm trees and 72-degree breezes. They’re wrong. Upland sits at a higher elevation than most of its neighbors—starting around 1,200 feet and climbing as you head north toward the foothills. That elevation change matters. It means we get more rain than the basin below and, on those rare, magical winter mornings, a light dusting of snow that melts before your first cup of coffee is finished.
The August Heat is No Joke
Let’s be real. August in Upland is basically a survival sport. While the coastal cities are enjoying that marine layer, Upland is soaking in a high-pressure heat dome. According to data from the Western Regional Climate Center (WRCC), the average high in August sits around 93°F, but that’s just the average. We regularly see "heat-health events" where the thermometer pushes 105°F for days at a time.
It’s dry heat, though. That’s the silver lining.
Humidity usually bottoms out in the 30% range during the summer. You won't feel that sticky, East Coast swamp air, but you will feel the sun literally baking the moisture out of your skin. If you’re planning a move here or just visiting, understand that the "feels like" temperature is often exactly what the thermometer says.
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Why the Mountains Matter
Upland is tucked right against the base of the San Gabriels. This creates an "orographic lift" effect. Basically, when moist air from the Pacific hits those mountains, it’s forced upward, cools down, and dumps rain. This is why Upland historically averages about 17 to 20 inches of rain a year, which is significantly more than cities just a few miles further south.
In 2026, we’re seeing these patterns shift. Climate trends show that while our total rainfall might stay somewhat stable, it’s coming in much more violent, concentrated bursts—think atmospheric rivers rather than gentle spring showers.
The Devil Winds: Surviving the Santa Anas
You can’t talk about weather for Upland California without mentioning the Santa Anas. Locally, we call them the "Devil Winds." They usually kick up in the fall, particularly October and November, though they can happen well into the winter.
These aren't your typical breezes.
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The wind starts in the high deserts of Nevada and Utah. As it drops down toward the coast, it compresses. Physics tells us that compressed air heats up—fast. By the time it hits Upland, it’s hot, incredibly dry (sometimes under 10% humidity), and moving at 40 to 60 miles per hour.
- The Dust Factor: It gets everywhere. Your car, your lungs, your window sills.
- The Fire Risk: This is the scary part. The combination of dead summer brush and high-velocity wind turns the foothills into a tinderbox.
- The Clear Skies: Paradoxically, the day after a Santa Ana wind event often produces the most stunning, crystal-clear views of the mountains you’ll ever see.
Winter is Basically Spring (With a Catch)
January and February are the "cold" months. In Upland terms, "cold" means a high of 65°F and a low of 42°F. It’s actually quite pleasant. Most days are sunny. You’ll see people in shorts and hoodies, which is the official uniform of the Inland Empire.
However, don't let the sunshine fool you. When those winter storms hit, they hit hard. The National Weather Service often issues flash flood warnings for the streets near the Euclid Avenue median because the runoff from the mountains has nowhere else to go.
Air Quality: The Hidden Trade-off
We have to talk about the smog. It sucks, but it's part of the package. Because Upland is a "bowl" created by the mountains, air pollution from Los Angeles gets pushed inland by the sea breeze and gets trapped against the San Gabriels.
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"Smog season" officially starts in May. On hot, stagnant days, the ground-level ozone can reach "Unhealthy for Sensitive Groups" levels. If you have asthma or like to run marathons, you’ll want to check the South Coast AQMD app before heading out. Surprisingly, the air quality has actually improved over the last decade due to stricter emissions laws, but on a triple-digit July day, you can still see that brownish haze hugging the horizon.
When Should You Actually Visit?
If you have a choice, aim for April or May.
The hills are still green from the winter rains. The wild lilac is blooming in the foothills. The temperature hovers in the mid-70s. It’s perfect. October is a close second, provided a Santa Ana wind isn't blowing your hair off.
Quick Facts for Your Calendar
- Hottest Month: August (Average 93°F).
- Coldest Month: December/January (Average low 40°F).
- Wettest Month: February (Expect about 3-4 inches).
- Best View: January, right after a rainstorm when the snow caps Mt. Baldy.
The weather for Upland California is a study in contrasts. It’s a place where you can go skiing at Mt. Baldy in the morning and be sitting by a pool in 80-degree weather by the afternoon. It's beautiful, but it requires a bit of preparation.
Practical Tips for Upland Weather
- Hydrate Constantly: The low humidity in the summer and during wind events will dehydrate you before you feel thirsty.
- Sunscreen is Non-Negotiable: At this elevation and with 350+ days of sun, you will burn in 15 minutes.
- Layer Up: The temperature swing between day and night can be 30 degrees. Always keep a sweater in the car.
- Check the AQI: Especially in the summer, monitor the air quality index if you plan on doing strenuous outdoor activities.
- Garden Smart: If you're planting, stick to drought-tolerant California natives that can handle the Santa Ana winds and the July heat spikes.