If you’ve lived in Southern California long enough, you know the drill. The Los Angeles news says it’s a breezy 72 degrees, but you step outside in Montclair and it feels like the sun is personally trying to settle a debt with you. Checking the weather for Montclair CA isn't just about looking at a number on your phone. It’s about understanding that weird little pocket of the Inland Empire where the coastal breeze goes to die and the Santa Ana winds come to play.
Honestly, it’s a microclimate thing.
You’re sitting right at the base of the San Gabriel Mountains. That geography does some funky stuff to the air. Today, January 14, 2026, we’re seeing a high of 79°F. That’s pretty warm for January, but not unheard of here. The sky is clear, and the humidity is sitting at a dry 30%. It’s basically perfect patio weather, provided you don't mind a little chill once the sun drops behind the peaks.
The Reality of Montclair’s Temperature Swings
Most people look at the averages and think they’ve got it figured out. They see an average August high of 92°F and think, "Okay, hot but manageable."
They’re wrong.
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In Montclair, the "average" is a liar. You’ll have weeks where the mercury doesn't drop below 100°F. Then, out of nowhere, a marine layer manages to squeeze through the Cajon Pass or over the Chino Hills, and suddenly you’re reaching for a hoodie. According to historical data from the National Centers for Environmental Information (NCEI), the variation here is way more dramatic than what you find in places like Pasadena or even nearby Rancho Cucamonga.
Winter is a different beast.
Last night it hit 47°F. By noon today, it’ll be 30 degrees warmer. That’s a massive swing for your body—and your HVAC system—to handle. While December and January are technically the "cool" months, they are often punctuated by Santa Ana wind events that can spike temperatures into the 80s while dropping humidity to single digits. It’s a dry heat that makes your skin feel two sizes too small.
When Does It Actually Rain?
Rain in Montclair is like a rare Pokémon sighting. You know it exists, but you rarely see it in the wild.
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We get most of our moisture between late November and early April. February is usually the wettest month, averaging about 2.9 inches. But here’s the kicker: it usually comes all at once. We don't really do "drizzle." We do "atmospheric rivers" that turn the local washes into raging torrents and make the 10 Freeway a nightmare of hydroplaning Teslas.
- Summer (June–August): Bone dry. 0.0 inches is the standard.
- Fall (September–November): Maybe a rogue thunderstorm if the monsoonal moisture creeps up from Mexico.
- Winter/Spring (December–March): This is your window. If it doesn't rain now, the wildfire season is going to be brutal.
Because we’re in a "rain shadow" sorta situation, the clouds often dump their loads on the mountains first. You’ll see the peaks of Mt. Baldy getting hammered with snow while you’re standing in Montclair under a light mist. It’s frustrating if you like rain, but great if you hate car washes.
Managing the Montclair Microclimate
If you’re new to the area, or just trying to survive another season, there are a few things you’ve gotta do. The weather for Montclair CA demands a specific kind of lifestyle adjustment.
First, the "dryness" isn't just a comfort issue; it's a health thing. When the humidity drops below 20%, nosebleeds and static shocks become a way of life. Experts at UC Agriculture and Natural Resources suggest that the "urban heat island" effect—all that asphalt at the Montclair Place mall and surrounding plazas—keeps the city several degrees warmer than the surrounding rural areas long after sunset.
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Practical Tips for the Local Climate
- Hydrate your house. Seriously. If you have wooden furniture or instruments, get a humidifier for the Santa Ana season. The air will literally suck the moisture out of your floorboards.
- The "Three-Layer" Rule. In winter, you start with a t-shirt (for the 75-degree afternoon), a light sweater (for the morning shade), and a heavy jacket (for when the sun goes down at 5:00 PM).
- Watch the Winds. If the NWS issues a High Wind Warning, move your trash cans. The way the wind funnels through the canyons to our north means Montclair gets hit with gusts that can easily top 50 mph.
- Landscaping. Don't try to grow a lush English garden here. You’ll spend $400 a month on water and it’ll still die in July. Stick to California natives or succulents that laugh at 100-degree days.
What to Expect for the Rest of the Week
Looking ahead, the ridge of high pressure is staying put. Tomorrow, January 15, we're looking at 76°F. Friday is almost a carbon copy. We might see some clouds roll in by Saturday or Sunday, but the chance of actual rain is hovering around a measly 5% to 10%.
Basically, keep the car windows up if you’re parking in the sun, and don't forget the sunscreen. Just because it’s January doesn't mean the UV index isn't sneaking up on you.
To stay ahead of the shifts, keep an eye on the local wind reports specifically for the Inland Empire. The general LA forecast often misses the localized gusts that hit the Montclair-Upland border. Check your tire pressure as the temperatures fluctuate; those 30-degree daily swings are notorious for triggering "low pressure" sensors. Ensure your irrigation timers are adjusted for the current dry spell to prevent plant stress before the next potential rain window in February.