Havana is one of those places where the weather doesn't just happen; it dominates the conversation at the diner and dictates exactly what you’re doing on a Saturday morning. People from outside Mason County usually think "Illinois weather" and picture flat cornfields and a breeze, but being tucked right against the Illinois River changes the game.
Today, Sunday, January 18, 2026, it is honestly pretty biting out there. We’re looking at a high of 23°F and a low of 2°F. If you’ve stepped outside, you already know that 9 mph southwest wind makes it feel more like 14°F. It’s cloudy, grey, and has that classic mid-winter "Havana gloom" that makes you want to stay inside with a second pot of coffee.
The River Factor and Why It Matters
You can't talk about weather for Havana Illinois without mentioning the river. It’s the lifeblood of the town, but it also creates a microclimate that can be a bit of a headache.
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Humidity here isn't just a summer thing. Even today, we're sitting at 49% humidity, which in sub-freezing temperatures, makes the cold feel damp and bone-deep. It’s the kind of cold that finds the gaps in your coat.
Most people worry about the big floods—like the record-breaking 32.94 feet crest back in April 2013—but the daily reality is more about how the water affects local fog and frost. When the Illinois River is warmer than the air in late autumn or early spring, you get that thick, "can't see your hand in front of your face" fog that rolls right into the downtown streets.
What the Next Few Days Look Like
If you’re planning your week, don't get too comfortable with these 20-degree highs. Monday is going to be even colder, dropping to a high of 12°F despite the sun coming out.
Basically, it’s a roller coaster. By Tuesday and Wednesday, we’re swinging back up to 35°F. That 23-degree jump sounds nice, but it usually comes with a messy slush because the ground is still frozen solid.
- Monday, Jan 19: Sunny but freezing. High of 12°F, low of 2°F.
- Tuesday, Jan 20: Back to clouds. High of 35°F, low of 7°F.
- Friday, Jan 23: Brace yourself. The high is only 9°F and we're looking at a low of -2°F.
The Extreme Reality of Mason County
Havana holds a bit of a reputation for temperature swings. The record high here is a staggering 113°F, set during the infamous heatwave of July 1936. On the flip side, we’ve seen it drop to -26°F in the winter.
That’s a 139-degree variance.
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Farmers around here have to be meteorologists by trade. The sandy soil in Mason County—thanks to the ancient riverbeds—heats up and cools down differently than the heavy clay you find further inland toward Springfield. It’s why Havana can sometimes feel like its own little island of weather.
Why Winter Isn't Just Snow
We get about 25 inches of snow a year on average, but the real hazard is the ice. Because we’re in that transition zone in the Midwest, we often get "winter mix" instead of clean snow.
One day it’s 34 degrees and raining, the next it’s 10 degrees and your driveway is a skating rink. Today’s 10% chance of snow is negligible, but by next Wednesday, the chance of snow showers jumps to 25%. It’s never enough to bury the town, just enough to make the commute on Route 136 a bit of a gamble.
Practical Advice for Navigating Havana’s Forecast
If you're moving here or just visiting the Chautauqua National Wildlife Refuge, stop looking at "Illinois" averages. Look at the river.
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- Check the Gauge: If you live near the waterfront, the USGS gauge at Havana is your best friend. Minor flood stage starts at 14 feet. If the forecast calls for heavy rain upstate in Peoria or Chicago, you’ll see those levels rise here a few days later.
- Layering is Real: With a low of -2°F coming Friday, you need more than just a heavy coat. Wind resistance is key because the wind coming off the open river valley has nothing to block it.
- The Humidity Trap: In the summer, Havana hits 86°F in July on average, but the humidity from the river and the surrounding cornfields (transpiration is a beast) can push the heat index over 100°F easily.
The weather here is predictable only in its ability to change. One day you're watching the ice floes on the river, and three months later, you're dodging a thunderstorm that popped up out of nowhere because of the heat rising off the valley floor.
Keep an eye on the wind direction. Today’s 12 mph southwest wind is typical, but when it shifts to the north later this week, that’s when you’ll really feel the "deep freeze" kick in. Stay warm, keep the salt bucket by the door, and maybe wait until Wednesday for any long outdoor projects.
Next Steps for Staying Safe:
- Ensure your vehicle's antifreeze levels are checked before Friday's -2°F low.
- Monitor the Illinois River levels if you have property in the low-lying areas near Liverpool or the Havana riverfront.
- Stock up on supplies before the Wednesday snow showers, as even light accumulation can slick up the rural Mason County roads quickly.