Pool season · Oregon
Hillsboro Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
One bar, one year, one Hillsboro pool. The season bar below draws everything the model knows — opening window, prime season, closing window — against today's date, with the working details one click away on the opening and closing pages.
Reading it takes ten seconds: 52 dots, one per week. Solid teal is Hillsboro's swim season; the hollow teal run before it (May 27 to June 17) is when to open; the hollow amber run after is when to close, with September 30 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.
The Hillsboro pool calendar
Opening — target June 3
Target June 3; the practical window runs May 27–June 17, and the 7-day mean crosses the 61°F threshold around June 17. Cold-water starts are the cheap ones.
Closing — deadline September 30
The window opens September 20 once water leaves the algae zone; the model deadline is September 30, a week ahead of the October 23 freeze normal.
Estimated water temperature by month
This is Hillsboro's typical-year water curve: the same EWMA model as the live widget, run on the 1991–2020 normals instead of this week's weather.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 40° | 41° | 44° | 48° | 54° | 59° | 64° | 68° | 65° | 57° | 48° | 42° |
The curve peaks near 68°F — comfortable-water months here usually involve a heater or a solar cover.
Email me when Hillsboro hits the closing window
Data: NOAA 1991–2020 climate normals via Portland-hillsboro Airport (1.1 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.