Pool closing · Tennessee
When to Close Your Pool in Morristown, TN: Deadline, Window & Checklist
Last updated: July 15, 2026 · Model window year: 2026 · dates · checklist · FAQ
Plan to close your Morristown pool by October 19. The local 7-day mean temperature drops out of the algae-risk zone around October 9, and NOAA normals put the first 32°F freeze near October 28 — 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.
Morristown closing dates at a glance
| Closing window | October 9 – October 19 |
|---|---|
| Close by (deadline) | October 19 |
| First freeze, 50% probability | October 28 |
| Open by (recommended) | April 15 |
| Opening window | April 8 – April 29 |
| 61°F crossing (7-day mean) | April 29 |
| Swim-season length (80°F+ days) | 111 days |
| NOAA normals station | Morristown Radio Wcrk · 1.8 mi · 1344 ft |
A classic four-season pool calendar: open early into cold water, close late into cold water, and Morristown's 111 days of prime swimming sit safely in between.
Put dates aside and follow the water: the Morristown curve says roughly 55°F by mid-April, 72°F by mid-June, 76°F in mid-August, then back down through 61°F in mid-October. The summer ceiling sits near 77°F, and every window above is just a line drawn on this curve.
The 12-step Morristown 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
Start midweek for a weekend close: bring alkalinity and pH into their label ranges and let the water settle. What you seal under the cover is what the pool soaks in until spring.
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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.
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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
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.
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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
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
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
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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Store chemicals properly
Seal opened containers, keep oxidizers and acids separated, and store everything cool, dry, and locked away from kids and pets — exactly as each label describes.
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Remove and store ladders and rails
Pull ladders, rails, and the diving-board hardware; rinse, dry, and store them out of the weather. Anchor sockets get a dab of protectant so spring bolts turn freely.
What to buy before the rush
Every item below sells out somewhere in Tennessee 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.
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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
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
Centers under the cover so ice pushes inward, not outward.
How Morristown compares locally
Statewide context: across the 14 Tennessee cities we model, Morristown's October 19 deadline sits in the latest quarter. Nearby, Knoxville (40 mi) closes around October 21 and Kingsport (47 mi) around October 19 — treat gaps under a week as microclimate noise, not strategy. Spring planning restarts at the opening guide; the Morristown pool season page keeps the whole year in one view.
Every number on this page traces to one instrument cluster: Morristown Radio Wcrk, 1.8 miles west of Morristown's center at an elevation near 1344 feet. NOAA computed its 1991–2020 normals from roughly three decades of daily readings — long enough that one strange spring in Hamblen County barely moves the dates.
Field notes for Morristown 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.
The warm spell after you closed
A 78°F week in October doesn't mean reopening. Water under an opaque cover warms far less than air suggests, and a closed, balanced pool tolerates a warm stretch fine. Check the cover pump has somewhere to send rain, enjoy the weather, and leave the plumbing sealed.
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.
Morristown 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 Morristown's actual water; the normals say the durable cool-down arrives near October 9, and anything inside the window to October 19 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 Morristown's water cool through the mid-60s°F — around October 9 by our model — then close inside the window that ends October 19.
Do I need antifreeze in pool lines?
Only for lines you can't verify dry — a proper blowout makes antifreeze unnecessary. Where doubt remains, use pool-grade product at its label rate, never automotive. No freeze-probability normal is published near Morristown, so let the live forecast, not a calendar, tell you when freeze protection starts mattering.
How far should I drain my pool for winter?
Follow the cover's instructions first: solid covers usually want water a few inches below the skimmer; some mesh setups run higher with the skimmer sealed. The hard rule is never empty — hydrostatic pressure can lift or crack an empty pool, a far worse outcome than any freeze.
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. Morristown 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 Morristown?
Our model's practical deadline is October 19 — set by the cool-down plus ten days (the freeze normal, October 28, 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 October 9–October 19 window, none of that drama applies.
Email me when Morristown hits the closing window
Data: NOAA 1991–2020 climate normals via Morristown Radio Wcrk (1.8 mi); live outlook by Open-Meteo. Full attribution on the sources page. Model assumptions and error bars on methodology.