So, if you’re currently in Arnold, you’ve probably noticed the air feels like it’s trying to bite you. It’s not just your imagination. We are looking at a serious shift in the arnold mo weather forecast that has basically turned the local climate into a scene from a survival movie. Honestly, after a Friday that teased us with a high of 45°F, hitting a wall of 24°F today—Saturday, January 17—is a bit of a shock to the system.
The humidity is sitting at 45%, and with a northwest wind whipping through at 8 mph, that "feels like" temp of 16°F is the real story. Mostly cloudy skies are hanging over Jefferson County, and we are officially in the "bundle up or regret it" phase of January.
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What’s Actually Going on With the Temperatures?
Basically, we are entering a deep freeze. Today’s high is stuck at 24°F, which is a massive drop from yesterday’s 45°F. If you’re planning on being out late tonight, be ready for a low of 13°F. That’s cold even by Missouri standards.
Kinda weirdly, the humidity is dropping to about 38% today. Usually, that would mean a "dry" cold, but with 16 mph winds coming from the west, it just means the wind chill is going to be brutal. You’ve likely heard local meteorologists from places like KSDK or the National Weather Service mention "Weather Impact Alerts." That’s because the wind chill is expected to stay near or below zero in some spots through Sunday morning.
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- Today (Saturday): High of 24°F, Low of 13°F. Mostly cloudy, then clearing.
- Tomorrow (Sunday): High of 32°F, Low of 13°F. It’ll feel a tiny bit better, but still freezing.
- Monday: The bottom drops out. High of 20°F, Low of 12°F. This is the peak of the chill.
The Polar Vortex Rumors
You might hear people at the grocery store talking about the Polar Vortex. It's not just a buzzword. Experts like those at WeatherTrends360 have been tracking a weakening of the vortex in the second half of January 2026. When that thing wobbles, it spills Arctic air straight down into the Midwest. Arnold happens to be right in the path of these "surges."
It’s a classic Missouri January. One day you’re wearing a light jacket; the next, you’re looking for your heavy-duty thermal socks.
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Is Snow Coming to Arnold?
Right now, the chance of precipitation for today is pretty low—only about 10%. We saw some flurries yesterday, but today is looking mostly dry. However, the arnold mo weather forecast for the next week shows some "active" potential.
By Tuesday, we might see a brief "thaw" with a high of 39°F, but don’t get too comfortable. By next Saturday, January 24, the chance of snow showers or a rain-snow mix jumps up to 40%. The humidity is expected to spike to around 92% by Sunday the 25th, which usually points to some kind of messy precipitation.
Honestly, the real concern isn't a massive blizzard. It's the "frozen mix." When the temp hovers around 32°F and then drops, the roads in Arnold—especially those hills near the Meramec River—can turn into skating rinks.
Expert Safety Steps for the Chill
If you're dealing with these 13°F nights, there are a few things you actually need to do beyond just putting on a coat.
- Check your tire pressure. Cold air makes the pressure drop. A "low tire" light is basically the official dashboard icon of January in Missouri.
- Drip those faucets. If your pipes are on an exterior wall, let them drip. A $500 plumbing bill is a bad way to start the year.
- Space heater safety. According to the CPSC, these things cause about 25,000 fires a year. Keep them three feet away from anything that can burn. No exceptions.
Looking ahead, we might see a bit of a break toward the end of the month, but the "frigid" trend seems intent on sticking around. Basically, keep the salt bucket by the front door and the heavy blankets on the bed.
Next Steps for Arnold Residents:
Check your vehicle's antifreeze levels and ensure your outdoor pets have heated water bowls or are brought inside, as nighttime temperatures will consistently drop into the low teens over the next 48 hours.