Look, the 10 day forecast San Dimas is showing some wild swings right now. Honestly, if you’re living in the SGV, you know January is basically a coin toss between "is it summer?" and "where's my umbrella?"
Right now, San Dimas is sitting at 57°F under a cloudy night sky. The wind is barely a whisper—just 5 mph coming from the north. But don't let the chill tonight fool you. We're about to see some heat that feels more like June than January.
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The Heat Wave Nobody Expected
Basically, the next few days are going to be gorgeous. Maybe too gorgeous? Friday and Saturday are both hitting a high of 79°F. That’s nearly 15 degrees above the historical average of 65°F for this time of year. If you’re planning a hike at Bonelli Park or just trying to get some yard work done, Saturday is your peak window. It’ll be partly sunny with a very low 10% chance of rain.
The humidity is dropping too. We're looking at 23% humidity on Saturday. It's that dry, crisp California air that makes the sun feel way hotter than the thermometer says.
When the Rain Actually Hits
Kinda felt like we might dodge the winter rain, right? Well, the 10 day forecast San Dimas says otherwise. Enjoy the sun while it lasts because things take a turn late next week.
- Monday (Jan 19): Mostly sunny, high of 75°F. Perfect.
- Tuesday (Jan 20): Still sunny, high of 76°F.
- Wednesday (Jan 21): The clouds start rolling in. High of 73°F.
- Thursday (Jan 22): This is the pivot point. High of 70°F, but nighttime brings a 65% chance of light rain.
By Friday, January 23rd, the "real" winter arrives. We’re talking a high of only 66°F and a 65% chance of showers throughout the day. The low drops to 47°F. If you have outdoor plans for next weekend, you might want to have a Plan B.
Understanding the Microclimate
San Dimas is unique. Being tucked right against the foothills of the San Gabriel Mountains means we get different weather than Los Angeles or even Pomona sometimes. Historically, January is our coldest month. While we’re seeing 79°F now, the average low is usually 45°F.
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The wind patterns are interesting too. We're seeing mostly light breezes—around 2 to 6 mph—shifting from the northeast to the southeast. It’s not the Santa Ana wind event we sometimes fear this time of year, but it’s keeping things dry until that storm system pushes through on Thursday night.
What to Actually Wear
Since we’re dealing with a 30-degree swing between day and night, layers aren't just a suggestion; they're a survival tactic.
- Morning (5:00 AM - 9:00 AM): It’s 50°F. You need a real jacket.
- Afternoon (12:00 PM - 4:00 PM): It’s 79°F. You’re in a t-shirt.
- Evening (7:00 PM onwards): Humidity rises, temps drop back to the 50s. Back to the hoodie.
Honestly, the most important thing to watch in this 10 day forecast San Dimas is the UV index. Even though it's January, it's hitting a 3 on Monday and Tuesday. That’s enough to catch a burn if you’re out at the dog park for a few hours.
Preparation Checklist for the Coming Week
Check your sprinklers now. With the humidity down to 23% and temps near 80°F, your lawn is going to get thirsty. But—and this is key—be ready to shut them off by Thursday night when the rain probability jumps to 65%.
Clean those gutters this weekend. The transition from 76°F on Tuesday to rainy showers on Friday can be a mess if your drainage is clogged with leftover fall leaves.
Keep an eye on that Friday, January 23rd window. It’s the first real "washout" risk we’ve seen in a while, with rain chances staying high into Saturday morning before we clear up again on Sunday.