Pool closing · State guide
When to Close Your Pool in Hawaii
Last updated: July 15, 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.