Pool closing · Minnesota
When to Close Your Pool in Woodbury, MN: Deadline, Window & Checklist
Last updated: July 15, 2026 · Model window year: 2026 · dates · checklist · FAQ
Circle September 28 on the Woodbury calendar. Closing earlier traps warm, algae-friendly water under the cover; closing later gambles the plumbing against the first freeze, which the 1991–2020 normals place near October 12. The window opens September 18 — the live widget below shows how this year is actually tracking against it.
Woodbury closing dates at a glance
| Closing window | September 18 – September 28 |
|---|---|
| Close by (deadline) | September 28 |
| First freeze, 50% probability | October 12 |
| Open by (recommended) | May 10 |
| Opening window | May 3 – May 24 |
| 61°F crossing (7-day mean) | May 24 |
| Swim-season length (80°F+ days) | 55 days |
| NOAA normals station | St Paul · 5.9 mi · 900 ft |
A short season cuts both ways: every week opened before May 24 is a real slice of Woodbury's roughly 55-day warm-swim budget.
Four water checkpoints anchor Woodbury's year in the model: mid-April at about 43°F, mid-June at 66°F, mid-August near the 71°F peak zone, and mid-October easing through 52°F. The dates in the table are where those numbers cross the thresholds that matter.
The 12-step Woodbury winterizing checklist
The order matters more than the date: balanced water first, verified-dry lines before anything else freezes-proofs, and the cover only after everything below it is done. Work the list inside the window above.
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Balance the water a few days ahead
Three or four days before closing, adjust alkalinity and pH into label ranges. Balanced water is gentler on the liner, plaster, and equipment through the long covered months ahead.
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Deep-clean the pool
Make the last cleaning the best one of the year: full skim, full brush, careful vacuum. Debris left behind steeps all winter and greets you as April's water problem.
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Service the filter one last time
One final filter service per the manual — cartridges rinsed and stored dry indoors, sand or DE backwashed. Winter turns trapped gunk into concrete.
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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
Your cover's manual sets the number — commonly a few inches under the skimmer for solid covers, barely below normal for mesh. Stop there. The remaining water isn't laziness; it's ballast holding the shell in the ground.
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Blow out the lines and plug returns
Push air through skimmer, return, and cleaner lines until they run dry mist, then seat expansion plugs at each return while air still flows. This is the single most important freeze-protection step.
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Protect the skimmer
Give the skimmer something cheap to break: a guard bottle or rated plug absorbs the ice expansion that would otherwise split the housing.
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Add pool antifreeze where blowouts fall short
Antifreeze is the insurance policy for doubtful lines, not a replacement for the blowout: pool-grade product, label dosing, and only where air couldn't finish the job.
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Drain the equipment
Open every drain plug on the pump, filter, heater, and chlorinator, and store the plugs in the pump basket so spring reassembly is a one-stop hunt. Move what you can indoors.
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Set the air pillow and cover
Pillow first, cover second, tension last. A properly centered pillow turns the winter ice sheet from a wall-pressing ram into a harmless dome.
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Note this year's dates
Jot down when Woodbury's water actually cooled and when you closed. A two-line note beats memory next September 18 — your own yard runs a few days off any model, including ours.
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Winterize the water features
Waterfalls, slides, and spillover spas hold water in places gravity won't clear — blow those lines separately and plug them, or they'll be the one crack you find in spring.
What to buy before the rush
Every item below sells out somewhere in Minnesota every September. Stocking the short list before the rush costs nothing extra and saves the mid-project store run — the chemicals guide explains what each category actually does.
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Cover pump
Solid covers collect rain all winter; this is the drainage plan.
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Expansion plugs + skimmer guard
The blowout's finishing move — one per return, one for the skimmer.
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Pool antifreeze
Backup for unverifiable lines; label rate per foot of pipe.
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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.
How Woodbury compares locally
Two nearby data points to triangulate with: St. Paul, 9 miles from Woodbury, models its close at September 30 (2 days later); Minneapolis, 17 miles out, at September 30. Woodbury's own window ends September 28. For the other half of the calendar see when to open in Woodbury, or scan the full year on the season page.
Every number on this page traces to one instrument cluster: St Paul, 5.9 miles northwest of Woodbury's center at an elevation near 900 feet. NOAA computed its 1991–2020 normals from roughly three decades of daily readings — long enough that one strange spring in Washington County barely moves the dates.
Field notes for Woodbury owners
What comes indoors
Cartridges, the cover pump when idle, chemical containers, and anything with a small motor overwinter better in the garage. Cold cycling is hard on plastics and seals; shelf space is cheaper than replacements. Label a single bin now and spring assembly becomes a scavenger hunt with a map.
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 mesh-cover spring surprise, prevented in fall
Mesh-covered pools green up early because late-winter sun plus nutrient-carrying meltwater reaches the water. The fall counter-moves: close late and cold, dose the winter kit exactly per label, and plan an early-spring peek under the cover rather than a Memorial Day reveal.
Hard-winter homework
Where winter is long — Woodbury banks only about 55 warm-swim days — the closing carries months of load. Bury the effort where it counts: verified-dry lines, fully drained equipment, a skimmer guard, and a cover secured for real wind. A short season forgives a late opening; it never forgives a cracked pump.
Woodbury pool closing FAQ
What temperature should water be to close a pool?
Close once water holds below about 65°F — the point where algae go mostly dormant — and before hard freezes. In Woodbury, the 7-day mean drops through the threshold around September 18, so the window between then and September 28 is the sweet spot for a clean, stable close.
Can you close a pool too early?
You can, and warm-water closings are why "we opened to a swamp" stories exist. The fix is patience: let Woodbury's water cool through the mid-60s°F — around September 18 by our model — then close inside the window that ends September 28.
Do I need antifreeze in pool lines?
Treat antifreeze as a backup, not a substitute: the real protection is air in dry lines. Where a full blowout isn't possible, pool-grade antifreeze per label is cheap insurance against a cracked pipe — worth it anywhere freezes are routine, and Woodbury sees them from about October 12.
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?
Expect equipment damage first — cracked pump volutes, split filter tanks, ruptured heater exchangers — then plumbing leaks that surface at startup. In Woodbury, normals put the first freeze near October 12; everything after that date is borrowed time for an unwinterized system.
When is the last safe date to close in Woodbury?
The model draws the line at September 28 for Woodbury. It isn't arbitrary: the cool-down plus ten days (the freeze normal, October 12, leaves room to spare), and the whole closing sequence needs a working weekend of margin. The one exception that overrides any date — a hard freeze inside the 10-day forecast, which the widget above flags as urgent.
Email me when Woodbury hits the closing window
Data: NOAA 1991–2020 climate normals via St Paul (5.9 mi); live outlook by Open-Meteo. Full attribution on the sources page. Model assumptions and error bars on methodology.