If you’ve lived here long enough, you know the drill. You check the forecast for weather for mundelein illinois on a Tuesday, see "partly cloudy," and by Wednesday afternoon, you’re digging your car out of six inches of snow that wasn't supposed to be there.
Mundelein is in a weird spot. We’re close enough to Lake Michigan to get hammered by lake-effect bands, but far enough inland that the "lake cooling" in the summer sometimes just skips us entirely, leaving us to bake while Chicago stays breezy. Honestly, it's a bit of a meteorological toss-up every single day.
Right now, we're deep in the January grind. As of January 16, 2026, the current temperature is sitting at 22°F, but it feels like 11°F thanks to an 11 mph wind coming out of the south. It's cloudy, it's gray, and the humidity is a thick 84%. Basically, it's typical Mundelein winter—damp, cold, and a little bit biting.
✨ Don't miss: 100 Biggest Cities in the US: Why the Map You Know is Wrong
The Reality of the January Thaw and Arctic Surges
We just came off a weirdly warm start to the month. Nationally, the first week of January 2026 was one of the warmest in 40 years, and Mundelein definitely felt that "January Thaw." But don’t let that fool you. The Polar Vortex is starting to wobble, and that means the second half of this month is looking much more aggressive.
Today, Friday, January 16, we’re looking at a high of 35°F with snow showers likely—about a 49% chance during the day. But look at the drop coming. By Monday, January 19, the high is struggling to reach 6°F with a low of 2°F. That is a massive swing.
🔗 Read more: Cooper City FL Zip Codes: What Moving Here Is Actually Like
When you're looking at weather for mundelein illinois, you have to watch those wind directions. On Monday, we’re expecting west winds at 21 mph. In this part of Lake County, a west wind at those speeds in January doesn't just feel cold; it feels like it’s trying to peel the paint off your house.
Microclimates: The Diamond Lake Factor
Most people think all of Lake County shares the same air. Not true. Mundelein has its own little micro-climate quirks. Being situated near Diamond Lake and surrounded by a decent amount of open space to the west means we don't have the "urban heat island" effect that keeps Chicago a few degrees warmer.
💡 You might also like: Why People That Died on Their Birthday Are More Common Than You Think
- Summer Humidity: In July, our highs average 83°F, but the dew points can make it feel like a swamp.
- Winter Winds: Because we lack the skyscrapers to break up the wind, those prairie gusts hit Mundelein hard.
- The Snow Line: It’s common for Mundelein to get 4 inches of snow while Libertyville gets 2 and Vernon Hills gets a dusting.
Surviving the Mundelein "Lake Effect" Confusion
Everyone talks about lake-effect snow, but few realize that Mundelein is often on the "knife's edge" of these events. For a true lake-effect dump to hit us, the wind usually needs an easterly or northeasterly component to pull that moisture off Lake Michigan.
Just back in November 2025, we had an early-season event where a station just 1 mile NNE of Mundelein recorded 5.1 inches of snow. Meanwhile, areas further south only saw a dusting. It shows how localized this can be. If the wind is coming from the west—like it will be for most of next week—the lake actually does nothing for our snow totals; it just stays dry and frigid.
Mundelein Weather by the Numbers (Averages vs. Reality)
| Month | Avg High | Avg Low | The "Mundelein" Reality |
|---|---|---|---|
| January | 30°F | 16°F | Constant cloud cover (about 56% of the time). |
| May | 70°F | 49°F | Rapidly increasing humidity; "Muggy" days start appearing. |
| July | 83°F | 64°F | The hottest month, often peaking with high UV indices. |
| October | 61°F | 43°F | The start of the "cloudier" half of the year. |
What You Should Actually Do This Week
Given the forecast, there are a few things that actually matter for Mundelein residents right now. We're looking at a string of "snow shower" days from Saturday through Wednesday. While none look like a "Snowmageddon" event—most days have a 20-25% chance of snow—the cumulative effect on the roads like Route 45 and Route 176 can be a mess.
- Prep for Monday’s Deep Freeze: When the high is 6°F, your car battery is going to struggle. If it’s more than three years old, get it tested now before Sunday night.
- Watch the Pipes: With lows hitting 2°F and 3°F early next week, make sure your outdoor spigots are disconnected. If you have a kitchen sink on an exterior wall, leave the cabinet doors open to let the house heat in.
- Sign Up for Mundelein Alerts: The Village uses the CivicReady system. You can text MundeleinIL to 38276 to get the SMS alerts. This is way faster than waiting for the news to tell you if there's a local emergency or a sudden "Considerable" damage threat from high winds.
- Salt Early: Friday’s high of 35°F means things will melt, but Saturday’s drop to 19°F means a flash freeze. If you don’t salt your driveway Friday evening, it’ll be a skating rink by Saturday morning.
The weather for mundelein illinois is never just one thing. It’s a mix of Great Plains winds, Lake Michigan moisture, and that weird "January Thaw" that tries to trick you into thinking spring is early. It isn't. Stay warm, keep the salt handy, and maybe check those tires before the Monday cold snap hits.