Why that window
Two clocks run in spring. The comfort clock: once daily averages pass the low-to-mid 60s°F, water reaches genuinely swimmable temperature within a couple of weeks. The algae clock: a covered pool warms faster than an open one, and somewhere in the 50s°F water range algae wakes up under that cover with no chlorine to stop it. Opening inside — or slightly ahead of — your city's window satisfies both: you're circulating and sanitizing before algae hits stride, and swimming arrives on schedule.
Opening day, in order
Pull and clean the cover, top up water, reconnect the equipment, and get the pump turning over. Then test everything — chlorine, pH, alkalinity, stabilizer, calcium — and correct in that order. The dosing calculator turns your first reading of the year into exact amounts in cups and pounds, and the volume calculator nails down the gallon figure every dose depends on.
Frequently asked questions
When should I open my pool in Washington?
Across Washington's featured cities, typical openings run Jun 15 to Jun 30 — the stretch when each town's daily average climbs through the low-to-mid 60s°F and the water follows to ~70°F within a couple of weeks. Find your city in the table for its own window.
Is it bad to open the pool early in Washington?
No — early is the safe direction. An open, circulating, chlorinated pool in cool weather costs a little more in chemicals; a covered pool sitting warm without sanitizer is how you open to a swamp. If anything, err a week or two ahead of your window.
Why do the dates differ across Washington?
Because each city's dates come from its own NOAA 1991–2020 station records, and geography does the rest — elevation, latitude, coastlines, and urban heat spread the same milestone across weeks. That local spread is exactly what a national "open on Memorial Day" rule misses.