Pool closing · Iowa
When to Close Your Pool in Des Moines, IA: Deadline, Window & Checklist
Last updated: July 15, 2026 · Model window year: 2026 · dates · checklist · FAQ
Two dates decide a Des Moines closing: September 28, when the 7-day mean drops back through 61°F and the water goes algae-quiet, and October 8, the model deadline set a safe week ahead of the October 20 first-freeze normal. Everything on this page — live water estimate, window, winterizing sequence — exists to land you between them.
Des Moines closing dates at a glance
| Closing window | September 28 – October 8 |
|---|---|
| Close by (deadline) | October 8 |
| First freeze, 50% probability | October 20 |
| Open by (recommended) | April 29 |
| Opening window | April 22 – May 13 |
| 61°F crossing (7-day mean) | May 13 |
| Swim-season length (80°F+ days) | 91 days |
| NOAA normals station | Des Moines International Airport · 3.5 mi · 957 ft |
Des Moines's 91-day warm season leaves comfortable margins on both ends — the windows above aim you at the cheap-chemistry versions of each transition.
Four water checkpoints anchor Des Moines's year in the model: mid-April at about 49°F, mid-June at 71°F, mid-August near the 75°F peak zone, and mid-October easing through 56°F. The dates in the table are where those numbers cross the thresholds that matter.
The 12-step Des Moines winterizing checklist
A closing is a plumbing project with a chemistry warm-up. Start a few days ahead of your target date, keep every dose per its product label, and don't skip the photographs — spring-you reassembles from them.
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Balance the water a few days ahead
Start midweek for a weekend close: bring alkalinity and pH into their label ranges and let the water settle. What you seal under the cover is what the pool soaks in until spring.
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Deep-clean the pool
Brush, skim, and vacuum like company's coming. A pool that goes under the cover spotless comes out needing a rinse; one that goes under dirty comes out needing a project.
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Service the filter one last time
Send the filter into winter clean: backwash the sand or DE, rinse and dry the cartridges indoors. Media stored dirty over winter hardens into a spring problem no backwash fixes.
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Apply winter chemicals per label
Add a winterizing kit or your usual closing chemicals exactly as their labels direct for your volume, with the pump still circulating so everything distributes before shutdown.
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Lower the water level
Take the level down only as far as the cover's manual says — usually just below the skimmer for solid covers, higher for many mesh systems. An empty pool is never the goal; shells crack and shift without water's weight.
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Blow out the lines and plug returns
Air through every line — skimmer, returns, cleaner — until each blows dry mist, plugging returns while the air still pushes. Nothing else on this list protects as much plumbing per minute.
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Protect the skimmer
Install a skimmer guard bottle (or a plug rated for your skimmer) so ice that forms there crushes the sacrificial piece instead of cracking the skimmer body.
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Add pool antifreeze where blowouts fall short
If any line can't be verified dry, add pool-grade antifreeze per its label. Use only pool antifreeze — automotive products don't belong in pool plumbing.
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Drain the equipment
Nothing on the pad should hold water overnight: pull the drain plugs from pump, filter, heater, and feeder, stash them all in the pump basket, and carry the portable pieces indoors.
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Set the air pillow and cover
Float a centered air pillow, then land the cover and secure it the way its design intends — bags, cable, or straps. Ice sheets need somewhere to collapse inward, and the pillow is that somewhere.
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Stage the cover pump
Solid covers need drainage all winter: set a cover pump or siphon before the first storm, not after. Standing water strains seams and invites a mid-winter emergency.
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Remove and store ladders and rails
Pull ladders, rails, and the diving-board hardware; rinse, dry, and store them out of the weather. Anchor sockets get a dab of protectant so spring bolts turn freely.
What to buy before the rush
A small stack of supplies turns the checklist above into a single-weekend job. Buy before Des Moines's September rush and the whole list ships at leisure instead of sprinting.
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Expansion plugs + skimmer guard
Cheap rubber that stands between ice and your fittings.
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Pool antifreeze
For lines you can't verify dry — pool-grade only, per label.
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Winter closing kit
The under-the-cover chemistry, measured for your gallons.
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Air pillow
A soft target for the ice sheet, centered under the cover.
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Winter cover
Sized to overlap; the cheapest insurance the pool wears all winter.
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Cover pump
Solid covers collect rain all winter; this is the drainage plan.
How Des Moines compares locally
Two nearby data points to triangulate with: Waterloo, 91 miles from Des Moines, models its close at October 3 (about a week earlier); Cedar Rapids, 103 miles out, at October 2. Des Moines's own window ends October 8. For the other half of the calendar see when to open in Des Moines, or scan the full year on the season page.
The instrument behind this page is Des Moines International Airport, 3.5 miles southwest of Des Moines — the closest station publishing complete 1991–2020 daily temperature normals. Thirty years of its readings set every date above; your own yard adds or subtracts a degree with shade, wind, and pavement, which is what the window's width is for.
Field notes for Des Moines owners
Match the drainage plan to the cover
Solid covers shed nothing — they need a cover pump staged before the first storm and checked after each one. Mesh covers drain themselves but pass silt that settles all winter. Either way, the plan is decided in October, not improvised in January when the cover is an ice sheet.
Gas heaters get the manual, not a guess
Every heater brand sequences its winterizing differently — drain plugs, blower considerations, gas supply, control settings. The generic advice (drain fully, close the valve) is right but incomplete; ten minutes with your model's manual protects the most expensive component you'll winterize.
The skimmer is the most breakable part you own
Skimmer bodies crack because water freezes inside the throat with nowhere to push. A sacrificial bottle or spring-loaded guard absorbs that expansion for a few dollars. It's the highest-return item in the entire closing kit relative to what it protects.
Closing for a real winter
A Des Moines closing has to hold for months of freeze-thaw, not a few frosty mornings. Spend the effort where winters bite: prove every line dry, drain every vessel on the pad, guard the skimmer, and tension the cover for wind that will actually come. The reward is a spring opening that's a rinse, not a rebuild.
Des Moines pool closing FAQ
What temperature should water be to close a pool?
Cold enough that biology has clocked out — below 65°F and falling, ideally low 60s. The widget above tracks Des Moines's actual water; the normals say the durable cool-down arrives near September 28, and anything inside the window to October 8 closes clean.
Can you close a pool too early?
Early closing is the mistake the whole model is built to prevent from the other direction. A cover installed over 70°F water is a terrarium: sanitizer decays, algae compound, nobody looks for months. Des Moines's water isn't reliably out of that zone until about September 28 — the calendar's first cold weekend doesn't change that.
Do I need antifreeze in pool lines?
It depends entirely on your confidence in the blowout. Lines that blew fully dry need nothing; anything uncertain — low runs, water features, a stubborn cleaner line — gets pool-grade antifreeze at the label's rate per foot. With Des Moines's freeze clock starting near October 20, uncertainty is the thing to eliminate.
How far should I drain my pool for winter?
Less than most people think. Below the skimmer opening is the classic solid-cover target; mesh covers often specify higher water. The cover's own manual wins every argument, and "drain it completely" is never the answer — empty shells pop out of wet ground.
What happens if you don't winterize a pool?
Two failure modes. Where freezes reach the plumbing, expansion cracks pumps, filters, and fittings from the inside. Where they don't, an unwatched pool simply drifts green and unbalanced by spring. Des Moines has no published freeze normal to pin the date, so the winterizing above plus forecast-watching covers both risks.
When is the last safe date to close in Des Moines?
Our model's practical deadline is October 8 — set by the cool-down plus ten days (the freeze normal, October 20, leaves room to spare). Push much past it and you're winterizing in freeze-warning weather, rushing the blowout, and hoping the cover goes on before the first hard night. Inside the September 28–October 8 window, none of that drama applies.
Email me when Des Moines hits the closing window
Data: NOAA 1991–2020 climate normals via Des Moines International Airport (3.5 mi); live outlook by Open-Meteo. Full attribution on the sources page. Model assumptions and error bars on methodology.