In Chicago, the right time to close an inground pool is once nighttime temperatures start consistently dropping toward freezing — typically the second to final week of October. Close too early and you give up swim days for no reason; wait too long past that window and you risk frozen pipes, cracked equipment, and structural damage that costs far more to fix than closing would have cost to do.
We're often asked whether it's really necessary to winterize — also known as closing — a pool for the season. While it's tempting to skip the time, effort, or cost of closing a pool, it's necessary for Chicago pool owners to close their pool for the winter.
Winterizing your pool protects your investment from Chicago's cold, long, and often brutal winters. When the temperature drops below freezing and there's still water sitting in your pool, you run a high risk of damaging the pool's structure. Even if the freezing water doesn't cause structural damage, an unclosed pool is prone to breeding algae — meaning you'll have to completely clean it before you can open it again in the spring.
Chicago's unpredictable fall weather makes this decision genuinely tricky. An unexpected warm stretch can make you want to keep swimming a little longer; an early cold snap can catch you off guard. As a general rule, once nighttime lows are consistently approaching freezing, that's your signal that it's time to close rather than wait — the second to final week of October is when most Chicago-area pool owners hit that point. If you close before consistently cold weather sets in, you're simply losing usable pool days; if you wait past it, you're gambling with equipment that's expensive to replace.
The right closing date isn't purely about the calendar — it also depends on your specific pool and equipment. The exact closing process varies by pool type, and closing a pool incorrectly can cause real damage; in extreme cases, an improperly closed inground pool can actually pop out of the ground. If you're not confident about your pool's condition, its liner type, or how to close it correctly, that's the signal to bring in a professional rather than guess at the timing yourself. A professional pool service can assess your specific setup and tell you exactly when — and how — to close it.
For most inground pools, the general winterization process looks like this:
Because the exact process varies by pool type, it's worth doing your research — or hiring a professional — before it's time to close. As noted above, closing your pool incorrectly can cause real damage.
If you'd like to protect your pool before Chicago's winter comes down on us, and you live in the North Shore or Northwest suburbs of the Chicagoland area, we can help. Give us a call at 847-753-9771 or fill out a quote request form — we're happy to give you a free quote or more information about our pool winterization process. And when spring rolls back around, our guide on timing pool closing and opening in Chicago covers the reopening half of this same decision.
Do I really need to close my inground pool for winter in Chicago? Yes. Freezing temperatures with water still in the pool risk structural damage, and even without freeze damage, an unclosed pool is prone to algae growth that requires a full cleaning before you can reopen it in spring.
When should I close my pool in Chicago? Most Chicago-area pool owners close between the second and final week of October, once nighttime temperatures are consistently approaching freezing. Closing earlier sacrifices swim days for no benefit; closing later risks frozen pipes and equipment damage.
What happens if I close my pool too early or too late? Closing too early means losing usable swim days you didn't need to give up. Closing too late — after temperatures have dropped below freezing — puts your pool's structure and equipment at risk of freeze damage.
Should I close my pool myself or hire a professional? You can close it yourself if you're comfortable with the process, but the exact steps vary by pool type, and an incorrectly closed pool can suffer real damage — in extreme cases, an inground pool can even pop out of the ground if closed improperly. If you're unsure about your pool's condition or the right process for it, a professional service can assess your setup and handle it correctly.