About

About PoolWindow

Last updated: July 15, 2026

PoolWindow answers two questions for owners of private outdoor pools, city by city: when to open in spring, and when to close in fall. Not "sometime around Memorial Day" — an actual local date, derived the same way for every one of 698 covered cities, from public NOAA climate data.

Why this site exists

Almost all opening-and-closing advice on the internet is national, and national advice has to hedge: "when temperatures are consistently warm," "before the first freeze," "typically May." Meanwhile the actual answer is sitting in a public dataset — NOAA's 1991–2020 climate normals resolve your local warm-up and cool-down to the calendar day. We built the model once, documented it, and ran it for every city we could match to a qualifying weather station.

The result is deliberately narrow. You won't find pool construction advice, chemistry recipes, or product reviews here — just the calendar math, a live water-temperature estimate, and the standard checklists sequenced against your local dates.

What we are and aren't

This is a data-modeling site, not a pool service, laboratory, or standards body. The dates are a documented convention applied to published climate statistics — a planning tool, with its assumptions and error bars stated plainly on the methodology page. We never publish chemical dosages (product labels own that), and nothing here is health, safety, or engineering advice; the disclaimer spells that out.

How it stays honest

Three habits. Every number traces to a named source on the sources page. Every formula is public and simple enough to check with a spreadsheet. And every page names its weather station and the distance to it, because a model that hides its inputs is just an opinion with extra steps.

Found an error — a wrong station, a suspicious date, a broken page? Please say so via the contact page. Corrections ship in the next build, and every page's "Last updated" line tells you when that was.