Chicago's normal first freeze at O'Hare is October 19. That is the National Weather Service's 1991–2020 average, not a forecast — some years it comes a week early, some years Halloween passes without it. But every heating company in this city knows that date, which is why their calendars are already tightening and their January phones are already ringing.
Here is the useful way to think about the next two weeks: everything on this list is the same job in October that it is in January. The difference is that in October you pick the appointment time and pay the shoulder-season rate. In January you wait, and you pay what they ask.
Three things. What each one actually involves depends on what you own, so all four heating systems are spelled out.
1. Book the heating service (the right one)
"Get your furnace tuned up" is advice written for a suburban single-family home. Plenty of Chicago doesn't have a furnace at all.
Forced-air furnace
Ask specifically for a heat exchanger inspection, not a filter change with a receipt stapled to it. The heat exchanger is the metal wall separating combustion gases from the air you breathe. When it cracks, the fix is a replacement rather than a repair — in the thousands — and it is also the failure that can put carbon monoxide into your house.
Found in October, that is a scheduled job you can get competitive quotes on. Found in January, it is an emergency, a week of space heaters, and whatever the first available company charges.
While you are at it: change the filter, and test every carbon monoxide detector in the house. Illinois law requires CO detectors within 15 feet of every sleeping area. Detectors also expire — most have a 7 to 10 year service life printed on the back, and an expired detector fails silently. If you cannot find a date on yours, replace it. They cost less than dinner.
Steam or hot-water boiler with radiators
A different machine and a genuinely different service call. What you want:
- The low-water cutoff tested and flushed. This is the safety device that shuts the boiler down if the water level drops. It is also the part that sediment disables. A boiler that fires dry is a catastrophic failure, not an inconvenient one.
- The sight glass cleaned so you can actually read the water level.
- Every radiator bled, or its air vent checked. On a one-pipe steam system each radiator has a small air vent that lets air out so steam can get in. When one fails closed, that radiator stays cold no matter how hard the boiler works. They are inexpensive and replaceable — and replacing a stuck vent is frequently the whole fix for "the back bedroom is freezing."
Skip this and you get the classic vintage-building winter: one room at 80, the next at 58, and a boiler short-cycling its way toward a failure nobody budgeted for.
If you are in a condo or co-op, the boiler is almost certainly the building's, not yours. Which means your actual job here is different: raise it at the September or October association meeting, in writing, before the building is cold. The person who brings it up in October is the reason it gets serviced. The person who brings it up in January is in a hallway argument with a board that has no money allocated for it.
Mini-splits running in heat-pump mode
If your heat comes from mini-splits, those units are your furnace now.
- Pull and rinse the indoor filters yourself. They are washable, it takes about five minutes a head, and it is the single highest-value thing you can do. Let them dry fully before they go back.
- Run heat mode for ten minutes this week, while a problem is still a scheduling question.
- Confirm the defrost cycle works. A heat pump that cannot defrost ices over on the outdoor coil and quietly falls back to electric backup heat. It will not leave you cold — it will show up as a winter electric bill two or three times what you expected, and most people do not connect the two until spring.
- Clear the outdoor unit and think about snow. Heat pumps need airflow through the outdoor coil all winter, and they need the base clear of drifting snow and ice. If yours sits at grade where the plow throws snow or where roof melt drips onto it, that is worth solving now.
Window air conditioners
Nothing to service. They are item 2.
2. Close the openings before the first hard night
Two jobs, and the first is the expensive one to skip.
Outdoor spigots
Shut the interior valve that feeds the spigot, open the tap outside, let the line drain completely, then disconnect the hose.
The trap: many people believe a frost-proof sillcock makes this unnecessary. It does not. A frost-proof faucet shuts the water off well back inside the heated wall — which works perfectly, and fails completely if a hose is still attached. The hose holds water against the valve seat, that water freezes and expands, and the split happens inside the wall. Disconnecting the hose matters more than which faucet you have.
You do not find a split supply line in December. You find it in April, when the wall gets wet the first time the line is pressurized — and by then it is a plumber and a drywall crew.
In a condo or a three-flat, find the interior valve now, before it matters. In a lot of Chicago buildings it is in a common basement, a shared utility closet, or behind an access panel in a unit that is not yours, and exactly one person knows where. Ask the association or your neighbor in October. Nobody wants that conversation at 11pm on the first hard freeze.
Window air conditioners
Pull them. A unit left in the window all winter is a hole in your wall — heat leaves through the sleeve and around the housing, and moisture gets into the gap and freezes there, which is how sills and frames rot from the inside.
If a unit is genuinely too heavy to move alone, the fallback is a fitted insulated cover on the outside plus sealing the interior perimeter. But out is better than covered, every time. This is also the right moment to do the deep coil cleaning you could not do while it was installed.
3. Clear the gutters, and check where the downspouts point
Timing matters: after the leaves drop, before the first freeze. Doing it in early October means doing it twice.
Then check the downspouts, which is the part most people skip. You want water discharging at least four feet from the foundation. If your downspout ends in a splash block sitting flush against the house, move it — or add an extension.
Here is the mechanism, because it makes the stakes obvious. Clogged gutters in a Chicago freeze-thaw do two things at once. Water that cannot get into the gutter runs straight down the wall and pools at the foundation, where it finds every crack. And water trapped in a blocked gutter backs up under the shingles at the roof edge, refreezes, and builds an ice dam that pushes meltwater up under the roofing rather than off it. Foundation water and ice dams are both four- and five-figure problems, and both start as a Saturday nobody spent on a ladder.
Flat-roofed two- and three-flats: you probably do not have gutters at the front. You have interior roof drains or scuppers, and they clog with the same leaves. A blocked roof drain on a flat roof does not overflow off the edge harmlessly — it ponds, and standing water on a flat roof in a freeze is how membranes fail. Same deadline, different hardware.
And again, if you are in an association: this is building work, not your Saturday. Report it in October. The point is that it gets done before the first thaw, not who does it.
If you own a vintage Chicago building
Most of the housing stock in this city predates 1950, and it behaves differently in a freeze. Three things worth a look while you are at it:
- Storm windows and weatherstripping. Original wood windows are not automatically a problem, but the gaps around them are. Rope caulk, v-seal, or a fitted interior storm panel on the two or three worst windows will do more than anything else on a cold-air-infiltration list.
- Uninsulated pipes on exterior walls. In a lot of old buildings the kitchen or bath supply runs through an exterior wall cavity with no insulation. Pipe sleeve is a few dollars a length. A burst line in a finished wall is not.
- The attic, if you have access to one. Ice dams are mostly a heat-loss problem, not a gutter problem. Warm air escaping into the attic melts snow on the roof, that meltwater runs to the cold eave and refreezes. If your attic hatch is drafty or your insulation is thin and uneven, that is the root cause, and October is when you can still get someone to look at it.
The short version
None of this is exciting work to do. All of it is cheaper this month than next month, and dramatically cheaper than January. Pick the two hours.
Vesta Preferred Realty has been helping people buy and sell across Chicago's neighborhoods since 2009. If you have a question about your building — what needs to be done, what can wait, or what a repair means for what your home is worth — reach out. We would rather answer it now than after.
