Pool closing · Washington
When to Close Your Pool in Spokane Valley, WA: Deadline, Window & Checklist
Last updated: July 15, 2026 · Model window year: 2026 · dates · checklist · FAQ
Plan to close your Spokane Valley pool by September 27. The local 7-day mean temperature drops out of the algae-risk zone around September 17, and NOAA normals put the first 32°F freeze near October 15 — winterize between those dates and the water goes under the cover cold, clean, and easy to reopen. Below: today's water estimate, the full closing window, and a step-by-step winterizing checklist.
Spokane Valley closing dates at a glance
| Closing window | September 17 – September 27 |
|---|---|
| Close by (deadline) | September 27 |
| First freeze, 50% probability | October 15 |
| Open by (recommended) | May 23 |
| Opening window | May 16 – June 6 |
| 61°F crossing (7-day mean) | June 6 |
| Swim-season length (80°F+ days) | 70 days |
| NOAA normals station | Spokane Felts Field · 4.3 mi · 1953 ft |
Spokane Valley banks only about 70 days of 80°F-plus afternoons — early opening weeks are the cheapest season extension available.
Four water checkpoints anchor Spokane Valley's year in the model: mid-April at about 47°F, mid-June at 62°F, mid-August near the 72°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 Spokane Valley winterizing checklist
Sequenced against Spokane Valley's September 17–September 27 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
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
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
Check the cover manufacturer's spec before touching the hose: solid covers typically want water below the skimmer mouth, mesh often barely lower than normal. Full draining is off the table entirely.
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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
Seat a skimmer guard or bottle in the throat — ice that forms there needs a sacrifice, and a two-dollar bottle beats a plumbing repair under the deck.
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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 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 Spokane Valley's water actually cooled and when you closed. A two-line note beats memory next September 17 — your own yard runs a few days off any model, including ours.
What to buy before the rush
Every item below sells out somewhere in Washington 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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Pool antifreeze
Pool-rated glycol for the lines air couldn't clear.
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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.
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Winter cover
Sized to overlap; the cheapest insurance the pool wears all winter.
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Cover pump
Standing water is a cover killer; this is the counter.
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Expansion plugs + skimmer guard
Cheap rubber that stands between ice and your fittings.
How Spokane Valley compares locally
Two nearby data points to triangulate with: Spokane, 9 miles from Spokane Valley, models its close at September 27 (the same day); Coeur d'Alene, 21 miles out, at September 26. Spokane Valley's own window ends September 27. For the other half of the calendar see when to open in Spokane Valley, or scan the full year on the season page.
Every number on this page traces to one instrument cluster: Spokane Felts Field, 4.3 miles west of Spokane Valley's center at an elevation near 1953 feet. NOAA computed its 1991–2020 normals from roughly three decades of daily readings — long enough that one strange spring in Spokane County barely moves the dates.
Field notes for Spokane Valley 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.
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.
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.
Hard-winter homework
Where winter is long — Spokane Valley banks only about 70 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.
Spokane Valley 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 Spokane Valley's actual water; the normals say the durable cool-down arrives near September 17, and anything inside the window to September 27 closes clean.
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 Spokane Valley's water cool through the mid-60s°F — around September 17 by our model — then close inside the window that ends September 27.
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 Spokane Valley the freeze clock starts around October 15, 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?
The repair list writes itself in order of cost: heater heat exchanger, pump housing, filter tank, then every fitting the ice reached — discovered one leak at a time in spring. Around Spokane Valley the exposure begins near October 15, and each skipped checklist step above is one more candidate for that list.
When is the last safe date to close in Spokane Valley?
The model draws the line at September 27 for Spokane Valley. It isn't arbitrary: the cool-down plus ten days (the freeze normal, October 15, 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 Spokane Valley hits the closing window
Data: NOAA 1991–2020 climate normals via Spokane Felts Field (4.3 mi); live outlook by Open-Meteo. Full attribution on the sources page. Model assumptions and error bars on methodology.