Pool closing · State guide
When to Close Your Pool in Hawaii
Last updated: July 25, 2026 · 2 cities covered
Every covered Hawaii city models as year-round: the 7-day mean temperature never drops below the 61°F algae threshold at any of the 2 cities' stations, so there is no forced closing deadline anywhere in the state. Each guide below covers the winter care routine instead.
Dates in the table are replaced by season length — the number of days with a normal high of 80°F or better — which is the number that actually varies across Hawaii.
| City | Window opens | Close by | First freeze (50%) |
|---|---|---|---|
| Honolulu | optional | no deadline | — |
| Kailua | optional | no deadline | — |
Dates are typical-year model outputs, not forecasts — each city guide carries the live widget that tracks the current year against them.
How to use these dates
Each "close by" deadline is the model's two-clock compromise for that city: ten days after its 7-day mean temperature falls back through 61°F (water goes algae-dormant soon after), but never later than a week before its 50% first-freeze date from the NOAA 1991–2020 normals. Closing inside the window seals cold, stable water under the cover; closing early seals a warm algae incubator instead.
Treat the dates as typical-year guidance, not forecasts. An early cold snap moves the real deadline — each city guide runs a live water-temperature widget that flags a 32°F night inside the 10-day forecast as urgent, and carries the full winterizing checklist in working order.
What drives Hawaii's closing deadlines
Tropical warmth and steady trade winds keep Hawaii pools open every month of the year, with passing windward showers rather than cold the only real interruption.