Pool closing · California
When to Close Your Pool in Redlands, CA: Deadline, Window & Checklist
Last updated: July 15, 2026 · Model window year: 2026 · dates · checklist · FAQ
Target November 23 as the practical closing deadline in Redlands. Our model of NOAA 1991–2020 normals keeps the 7-day mean above 61°F until November 13; after that, cooling water winds algae down while you work the checklist below. The hard stop is equipment freeze damage — normals put Redlands's first 32°F night near December 19.
Redlands closing dates at a glance
| Closing window | November 13 – November 23 |
|---|---|
| Close by (deadline) | November 23 |
| First freeze, 50% probability | December 19 |
| Open by (recommended) | March 29 |
| Opening window | March 22 – April 12 |
| 61°F crossing (7-day mean) | April 12 |
| Swim-season length (80°F+ days) | 166 days |
| NOAA normals station | Redlands · 1.7 mi · 1410 ft |
Redlands's 166-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 Redlands's year in the model: mid-April at about 61°F, mid-June at 71°F, mid-August near the 80°F peak zone, and mid-October easing through 70°F. The dates in the table are where those numbers cross the thresholds that matter.
The 12-step Redlands 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
Give the chemistry a head start — balance to label ranges several days out, while circulation can still mix corrections evenly. Closing-day dosing never distributes as well.
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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
Dose the winter kit while the pump still runs — every product exactly per its label for your volume — so the chemistry is fully mixed before the system goes quiet.
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Lower the water level
Drop the level as your cover manufacturer specifies — typically below the skimmer mouth for solid covers. Never drain a pool fully; groundwater pressure can damage the shell.
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Blow out the lines and plug returns
The blowout is the whole ballgame: drive air through each line until it runs dry, seat the plug against the airflow, move to the next. A dry line cannot burst, full stop.
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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
Any line you can't prove is dry gets pool-grade antifreeze at the label's rate per foot. Automotive antifreeze is toxic in this context — pool-rated only, always.
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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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Calendar the off-season checks
Set a monthly reminder from November 23 to spring: check cover tension, pump off standing water, and glance at the water level. Fifteen minutes a month protects the whole closing job.
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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
The November crowd empties shelves in a predictable order. This is the short list worth owning before Redlands's window opens — nothing exotic, just the stuff everyone needs the same weekend.
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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.
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Expansion plugs + skimmer guard
Cheap rubber that stands between ice and your fittings.
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Pool antifreeze
Backup for unverifiable lines; label rate per foot of pipe.
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Winter closing kit
Season-length winter chemicals in one label-dosed box.
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Air pillow
A soft target for the ice sheet, centered under the cover.
How Redlands compares locally
Statewide context: across the 147 California cities we model, Redlands's November 23 deadline sits in the earlier half. Nearby, Moreno Valley (9 mi) closes around November 23 and San Bernardino (9 mi) around November 23 — treat gaps under a week as microclimate noise, not strategy. Spring planning restarts at the opening guide; the Redlands pool season page keeps the whole year in one view.
The instrument behind this page is Redlands, 1.7 miles southwest of Redlands — 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 Redlands owners
Leaf season vs closing day
If your yard drops serious leaves, the cheap trick is a leaf net over the main cover through the drop, then one bulk removal before snow. Leaves that winter on (or worse, under) the cover steep like tea and hand you stained water and clogged pumps in spring.
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.
Blowout first, antifreeze second
Air is the only guaranteed freeze protection: a line that's verifiably dry cannot burst. Antifreeze (pool-grade, per label) is the fallback for lines you can't confirm — long runs, low spots, water-feature plumbing. Doing antifreeze instead of a blowout, rather than in addition, is how most cracked returns happen.
Redlands 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 Redlands, the 7-day mean drops through the threshold around November 13, so the window between then and November 23 is the sweet spot for a clean, stable close.
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. Redlands's water isn't reliably out of that zone until about November 13 — the calendar's first cold weekend doesn't change that.
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 Redlands the freeze clock starts around December 19, so settle this during closing, not during the first cold snap.
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 Redlands, normals put the first freeze near December 19; everything after that date is borrowed time for an unwinterized system.
When is the last safe date to close in Redlands?
November 23, by our model — the cool-down plus ten days (the freeze normal, December 19, leaves room to spare). Later closes happen, but they happen in gloves. The winterizing steps above take a weekend; leave yourself at least that much runway before Redlands's first freeze-risk stretch.
Email me when Redlands hits the closing window
Data: NOAA 1991–2020 climate normals via Redlands (1.7 mi); live outlook by Open-Meteo. Full attribution on the sources page. Model assumptions and error bars on methodology.