PoolWindow

The local dates to open and close your pool

Two dates decide your whole pool year. We compute both for 698 U.S. cities from NOAA 1991–2020 climate normals — open before the water hits the algae zone, close after the cool-down but before the first freeze — and track the live water temperature in between.

Pool opening →Your spring date, the 61°F crossing, and a 12-step cold-water startup checklist. Beat the May rush by weeks. Pool closing →Your fall deadline between the algae cool-down and the first 32°F freeze, plus the full winterizing sequence.

How the model works

  1. Find the crossing. For each city we take the nearest NOAA 1991–2020 normals station and compute the 7-day mean temperature for every calendar day. The day it crosses 61°F, unheated pool water is on approach to the 65°F algae-growth zone.
  2. Work backward (and forward). Open two weeks before the spring crossing — cold water, cheap startup, stocked shelves. Close after the fall crossing, but no later than a week before the local 50% first-freeze date.
  3. Watch the live water. Every city page runs a water-temperature model on current Open-Meteo air data, so you can see where this year sits against the normals — and when a freeze inside the 10-day forecast turns the closing clock urgent.

Every threshold and formula is public on the methodology page — it's a site model built on published climate data, with honest error bars, not a lab result.

The biggest metros we cover

Model dates for the ten largest covered metros — every city links to its full local guides.
CityOpen byClose by80°F+ days
New York, NYApr 24Oct 1781
Los Angeles, CAMar 22Dec 80
Chicago, ILMay 12Oct 948
Miami, FLyear-round—203
Houston, TXFeb 18Nov 30186
Dallas, TXMar 7Nov 16170
Philadelphia, PAApr 15Oct 22109
Atlanta, GAMar 30Oct 30143
Washington, DCApr 13Oct 21115
Boston, MAMay 10Oct 676

Or jump straight to the calculator — pick any covered city and get both windows plus today's estimated water temperature. When the date is set, the practical guides take over: how to open a pool step by step (inground, above-ground, and salt water), the opening chemicals list, and an honest service-vs-DIY comparison.

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