Pool closing · Texas
When to Close Your Pool in McAllen, TX: Deadline, Window & Checklist
Last updated: July 15, 2026 · Model window year: 2026 · dates · checklist · FAQ
Target December 25 as the practical closing deadline in McAllen. Our model of NOAA 1991–2020 normals keeps the 7-day mean above 61°F until December 19; after that, cooling water winds algae down while you work the checklist below. The hard stop is equipment freeze damage — normals put McAllen's first 32°F night near January 1.
McAllen closing dates at a glance
| Closing window | December 19 – December 25 |
|---|---|
| Close by (deadline) | December 25 |
| First freeze, 50% probability | January 1 |
| Open by (recommended) | January 10 |
| Opening window | January 3 – January 24 |
| 61°F crossing (7-day mean) | January 24 |
| Swim-season length (80°F+ days) | 251 days |
| NOAA normals station | Mcallen · 2.4 mi · 100 ft |
With 251 days of 80°F-plus highs, McAllen is keep-it-open country for plenty of owners; the closing dates above matter most if you'd rather not maintain water you won't swim in.
Four water checkpoints anchor McAllen's year in the model: mid-April at about 75°F, mid-June at 86°F, mid-August near the 88°F peak zone, and mid-October easing through 80°F. The dates in the table are where those numbers cross the thresholds that matter.
The 12-step McAllen 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
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
Run the winter kit through moving water: dose each product per its label with the pump on, give it a few hours to distribute, then start the shutdown. Chemistry added to still water stays where it lands.
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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
Work line by line: push air until the return spits dry mist, plug it against the flowing air, move on. Skimmer, returns, cleaner line, in whatever order your plumbing prefers — dry pipes are the entire point of closing.
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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
Doubt is the criterion: any run you can't confirm dry gets pool-grade antifreeze at the label's per-foot rate. The automotive jug from the garage is for cars — it has no business in pool plumbing.
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Drain the equipment
Open the drains on everything that holds water and let the pad empty completely. Cartridges and small equipment overwinter far better on a garage shelf than outside.
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Set the air pillow and cover
Center an inflated air pillow, then fit the cover and secure it with water bags, cable, or straps as designed. The pillow gives ice a place to push besides your walls.
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Note this year's dates
Jot down when McAllen's water actually cooled and when you closed. A two-line note beats memory next December 19 — your own yard runs a few days off any model, including ours.
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Calendar the off-season checks
Set a monthly reminder from December 25 to spring: check cover tension, pump off standing water, and glance at the water level. Fifteen minutes a month protects the whole closing job.
What to buy before the rush
Every item below sells out somewhere in Texas every December. 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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Winter cover
Measure with overlap; the winter workhorse over everything else.
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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
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.
How McAllen compares locally
Statewide context: across the 68 Texas cities we model, McAllen's December 25 deadline sits in the earliest quarter. Nearby, Edinburg (8 mi) closes around December 26 and Harlingen (34 mi) around December 27 — treat gaps under a week as microclimate noise, not strategy. Spring planning restarts at the opening guide; the McAllen pool season page keeps the whole year in one view.
Every number on this page traces to one instrument cluster: Mcallen, 2.4 miles south of McAllen's center at an elevation near 100 feet. NOAA computed its 1991–2020 normals from roughly three decades of daily readings — long enough that one strange spring in Hidalgo County barely moves the dates.
Field notes for McAllen owners
Cold water is the whole point
A pool closed at 55°F barely changes all winter: algae are dormant, chemicals hold, and spring opens with a light dusting instead of a bloom. A pool closed at 72°F runs its own quiet ecosystem under the cover for a month. The date matters less than the water temperature it represents.
Cover pumps die in the cold — plan for it
A cover pump left running into a hard freeze can lock in ice and burn out. On freezing forecasts, pull it, let the storm pass, and put it back for the melt. Automatic models with freeze protection earn their price in exactly one forgotten weekend.
Salt cells overwinter indoors
Remove the cell at closing, inspect and clean per the manufacturer, and store it inside with the unions capped. A dummy cell or spacer keeps the plumbing sealed. Cells left in outdoor plumbing through freezes are a common — and completely avoidable — spring casualty.
Don't close a pool people are still using
With McAllen's long season, the question isn't "is it November?" but "has the water actually cooled?" The window running to December 25 exists because warm-water closings breed spring algae. If swimmers keep showing up through December, let them — patience here is free maintenance.
McAllen pool closing FAQ
What temperature should water be to close a pool?
The practical target is water in the low 60s°F or below at closing day. Our McAllen model has the sustained cool-down starting December 19; closing between then and December 25 means chemistry stays put and the spring reveal is a mild one.
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 McAllen's water cool through the mid-60s°F — around December 19 by our model — then close inside the window that ends December 25.
Do I need antifreeze in pool lines?
Blown-out, plugged lines don't need it; doubtful lines do. Use only antifreeze labeled for pools, at the label's rate per foot of pipe — never automotive antifreeze. In McAllen the freeze clock starts around January 1, so settle this during closing, not during the first cold snap.
How far should I drain my pool for winter?
As far as your cover manufacturer specifies and no farther — typically a few inches below the skimmer mouth for solid covers, near normal level for many mesh systems with skimmer plugs. Never drain fully: an empty shell can shift or crack under groundwater pressure.
What happens if you don't winterize a pool?
In a freeze climate, physics wins: water expands about 9% when it freezes, cracking pump housings, filter tanks, heat exchangers, and pipes. With McAllen's first 32°F night arriving near January 1 in the normals, an unwinterized pad is a spring repair bill waiting to be discovered.
When is the last safe date to close in McAllen?
Our model's practical deadline is December 25 — set by the cool-down plus ten days (the freeze normal, January 1, 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 December 19–December 25 window, none of that drama applies.
Email me when McAllen hits the closing window
Data: NOAA 1991–2020 climate normals via Mcallen (2.4 mi); live outlook by Open-Meteo. Full attribution on the sources page. Model assumptions and error bars on methodology.