When to Close Your Pool in Kennewick, WA: Deadline, Window & Checklist

Kennewick closing dates at a glance

Kennewick's 101-day warm season leaves comfortable margins on both ends — the windows above aim you at the cheap-chemistry versions of each transition.

The same model in water terms: Kennewick's estimated pool temperature runs about 53°F in mid-April, 68°F in mid-June, 77°F in mid-August, and 58°F in mid-October, peaking near 78°F. Those four checkpoints — not any calendar holiday — are what the windows above are protecting.

The 12-step Kennewick winterizing checklist

Sequenced against Kennewick's October 1–October 11 window: chemistry while the pump still runs, blowouts before the equipment drains, cover last. Labels dictate every dose.

1. 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.

2. Deep-clean the pool

   Skim, brush walls and steps, and vacuum carefully. Any leaves or algae you seal under the cover become spring's chemistry problem, so closing day cleanliness pays twice.

3. Service the filter one last time

   Backwash sand or DE, or pull and rinse cartridges, per the manual. A filter stored dirty cakes over winter and starts spring half-clogged.

4. 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.

5. 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.

6. 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.

7. 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.

8. 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.

9. Drain the equipment

   Every vessel on the pad — pump, filter, heater, chlorinator — gets its drain plugs pulled. Drop all the plugs in the pump basket; that's the one place everyone looks first in spring.

10. 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.

11. 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.

12. Note this year's dates

    Jot down when Kennewick's water actually cooled and when you closed. A two-line note beats memory next October 1 — 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 October. 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.

• Winter cover

  The one purchase every other closing step depends on.

• Cover pump

  Solid covers collect rain all winter; this is the drainage plan.

• Expansion plugs + skimmer guard

  The blowout's finishing move — one per return, one for the skimmer.

• Pool antifreeze

  For lines you can't verify dry — pool-grade only, per label.

• Winter closing kit

  Season-length winter chemicals in one label-dosed box.

• Air pillow

  Gives ice somewhere to push besides your pool walls.

How Kennewick compares locally

Kennewick closes in the earliest quarter of Washington's calendar. Neighbors run close: Pasco (4 mi away) models its deadline at October 4 (about a week earlier vs Kennewick's October 11), while Yakima (71 mi) shows October 6. The spring mirror of this page is the Kennewick opening guide, and the season overview draws both windows on a single bar.

The instrument behind this page is Kennewick, 3.5 miles east of Kennewick — 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 Kennewick owners

The skimmer is the most breakable part you own

Skimmer bodies crack because water freezes inside the throat with nowhere to push. A sacrificial bottle or spring-loaded guard absorbs that expansion for a few dollars. It's the highest-return item in the entire closing kit relative to what it protects.

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.

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.