FAQ
When should I open my pool in the Hamptons?
Earlier than the calendar says: when daytime air is consistently above 70°F, or overnight lows are holding at 60–65°F, and not later. The water will be far too cold to swim, and that is the point: algae is active, not dormant, at 70°F, and a pool that sits under a cover into May with warming water and no circulation opens green. On Long Island most residential pools open between mid-March and early May depending on the year. Closing works in reverse: watch for nighttime lows consistently below 50°F for several nights, which on Long Island usually arrives mid-to-late October (national sources disagree on the threshold, quoting 65°F, 60°F or 50°F water). Open-to-close is a five-to-seven-month season; the serviced part of it is usually about 20 weeks.
Last updated · Reviewed by Georgica Pool Co.
The rule, and why
Every trade source gives the same rule in slightly different words: open the pool when daytime temperatures are consistently above 70°F, and get the pump and filter running then. The reason is biology, not comfort. Algae goes dormant in cold water and wakes up as the water warms; a pool under a cover in late April is warm, dark, still and full of last fall's nutrients, which is a recipe. Circulation and chlorine before the water crosses about 70°F keep it clear. Circulation and chlorine two weeks after it crosses 70°F are a cleanup.
One source frames it by nights instead: open when overnight lows are consistently 60–65°F. Same idea.
On Long Island
Long Island pool companies open most residential pools between mid-March and early May. Which end of that window is right for your pool depends on the year and the site: an open, sunny pool south of the highway warms weeks before a shaded pool in Northwest Woods, and a dark solid cover warms the water under it faster than a mesh one. The practical version: when the forsythia is done and the forecast has a week of 70s, you are late.
The mid-April question
People open in mid-April because it is a date, not because it is a temperature. In a cold spring mid-April is early and harmless; in a warm one it is two weeks late. Watch the thermometer, and if the house is empty in April, ask the service company to watch it for you; that is what the seasonal programs' "first pick of opening dates" is for.
Closing, in reverse
Close too early and you trap warm water under a cover for six months; close too late and you risk a freeze with water in the lines. Sources disagree on the threshold. Hayward's guidance says water consistently below 65°F; others say 60°F, when algae goes dormant; a cautious minority say wait for 50°F water. The Long Island version, from a local builder, is the useful one: watch for nighttime lows consistently below 50°F for several nights running, which usually happens mid-to-late October in Nassau and Suffolk. Closing costs about the same as opening (from about $425 with one Hamptons company; $175–500 nationally depending on the source).
The season, honestly
Open-to-close on the South Fork runs roughly five to seven months. The serviced season is shorter: the seasonal programs sold here run about 20 weeks, which is Memorial Day to Columbus Day and a little either side. If you want the pool warm for Mother's Day, that is a heater conversation, not an opening-date one.
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