Pool closing · California
When to Close Your Pool in Hawthorne, CA: Deadline, Window & Checklist
Last updated: July 15, 2026 · Model window year: 2026 · dates · checklist · FAQ
Target December 2 as the practical closing deadline in Hawthorne. Our model of NOAA 1991–2020 normals keeps the 7-day mean above 61°F until November 22; after that, cooling water winds algae down while you work the checklist below. The hard stop is equipment freeze damage — normals put Hawthorne's first 32°F night near January 5.
Hawthorne closing dates at a glance
| Closing window | November 22 – December 2 |
|---|---|
| Close by (deadline) | December 2 |
| First freeze, 50% probability | January 5 |
| Open by (recommended) | March 15 |
| Opening window | March 8 – March 29 |
| 61°F crossing (7-day mean) | March 29 |
| Swim-season length (80°F+ days) | 0 days |
| NOAA normals station | Hawthorne Municipal Airport · 0.9 mi · 63 ft |
Hawthorne banks only about 0 days of 80°F-plus afternoons — early opening weeks are the cheapest season extension available.
Four water checkpoints anchor Hawthorne's year in the model: mid-April at about 62°F, mid-June at 66°F, mid-August near the 72°F peak zone, and mid-October easing through 69°F. The dates in the table are where those numbers cross the thresholds that matter.
The 12-step Hawthorne winterizing checklist
Sequenced against Hawthorne's November 22–December 2 window: chemistry while the pump still runs, blowouts before the equipment drains, cover last. Labels dictate every dose.
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Balance the water a few days ahead
Do the chemistry midweek, close on the weekend: alkalinity and pH into label ranges with days of circulation left to spread them. Winter locks in whatever state the water holds on closing day.
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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
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
Winter chemicals go in before shutdown, not after: label-dosed, circulated for a few hours, distributed evenly. A floater dropped on still water protects one corner.
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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
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
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
Inflate the pillow to about two-thirds, center it, then bring the cover over and secure it per its design. Under ice, that soft dome is the difference between inward compression and outward wall pressure.
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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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Note this year's dates
Jot down when Hawthorne's water actually cooled and when you closed. A two-line note beats memory next November 22 — your own yard runs a few days off any model, including ours.
What to buy before the rush
A small stack of supplies turns the checklist above into a single-weekend job. Buy before Hawthorne's November rush and the whole list ships at leisure instead of sprinting.
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Winter closing kit
Closing chemistry in one box, dosed by pool volume.
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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.
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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
Pool-rated glycol for the lines air couldn't clear.
How Hawthorne compares locally
Two nearby data points to triangulate with: Inglewood, 3 miles from Hawthorne, models its close at December 2 (the same day); Redondo Beach, 4 miles out, at November 25. Hawthorne's own window ends December 2. For the other half of the calendar see when to open in Hawthorne, or scan the full year on the season page.
Local means local: Hawthorne's dates come from Hawthorne Municipal Airport, the nearest station with complete daily temperature normals — 0.9 miles northeast, about 63 feet up. Between that station and a Los Angeles County backyard there's always a degree or two of microclimate; the windows are built wide enough to carry it.
Field notes for Hawthorne 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.
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.
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.
Closing for a real winter
A Hawthorne 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.
Hawthorne 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 Hawthorne, the 7-day mean drops through the threshold around November 22, so the window between then and December 2 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. Hawthorne's water isn't reliably out of that zone until about November 22 — 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 Hawthorne's freeze clock starting near January 5, uncertainty is the thing to eliminate.
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?
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. Hawthorne 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 Hawthorne?
December 2, by our model — the cool-down plus ten days (the freeze normal, January 5, 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 Hawthorne's first freeze-risk stretch.
Email me when Hawthorne hits the closing window
Data: NOAA 1991–2020 climate normals via Hawthorne Municipal Airport (0.9 mi); live outlook by Open-Meteo. Full attribution on the sources page. Model assumptions and error bars on methodology.