Pool opening is a local date, not a holiday
"Open Memorial Day, close Labor Day" is advice written for exactly one climate — nobody's. The same milestone is six weeks apart between Minneapolis and Dallas, and in Phoenix the question is almost moot. This lookup reads your own town's 1991–2020 NOAA temperature record and finds the stretch when daily averages move through the low-to-mid 60s°F — the band where an unheated pool goes from brisk to genuinely pleasant.
After a lookup, your town is remembered in your browser, so the calculators and city pages across the site can pick up where you left off. Nothing you type here is uploaded anywhere.
The two dates worth respecting
Opening has a hidden deadline: algae wakes up in a covered pool around the mid-50s°F water range, well before swimming weather. Open at — or slightly before — your window and the sanitizer is working before algae is. Closing is the reverse: wait until water holds below ~60°F, when algae is dormant, and the pool winters clean. Full city detail lives on the pool season pages.
Frequently asked questions
Where do these dates come from?
From 1991–2020 NOAA temperature records at the weather station nearest your town. The working rule: an unheated pool turns pleasant as the daily average air temperature climbs through the low-to-mid 60s°F — water lags the air by a week or two, so that crossing puts the water near 70°F soon after.
Why can I pick a water preference?
Because "warm enough" is personal. The three settings move the threshold the dates hang on: 62°F daily average for people who dive in early, 65°F for most swimmers, 68°F if you wait for genuinely warm water. The spread between them is usually two to four weeks on each end of the season.
My pool has a heater. Do these dates still apply?
They mark the unheated baseline. A heat pump or gas heater typically buys 3–6 extra weeks on each end; a solar cover alone adds a week or two by holding overnight warmth. Use the dates as the free-season core and the heater calculator to price the extension.
Should I wait for these dates to open the pool?
Opening earlier than your window is completely fine — an open, circulating, chlorinated pool in cool weather is healthy, just brisk. What costs you is the opposite: leaving a pool covered and unsanitized as the weather warms is the classic recipe for a green opening.