Pool season · Oregon
Portland Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
Portland's whole pool calendar, condensed: when the water warms, when it cools, and where today falls between those edges. Use the opening guide and closing guide for the step-by-step work; keep this page for the dates.
Portland, OR — 40 swim days a yearReading it takes ten seconds: 52 dots, one per week. Solid teal is Portland's swim season; the hollow teal run before it (May 11 to June 1) is when to open; the hollow amber run after is when to close, with October 10 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.
The Portland pool calendar
Opening — target May 18
Open by May 18 — a two-week head start on the June 1 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline October 10
Hold the cover until September 30, then winterize by October 10, a week ahead of the December 1 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
Monthly averages of the site's water model run on Portland's own normals — the shape of a typical year, not a forecast. The widget above shows where the current year actually sits.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 41° | 43° | 47° | 50° | 56° | 61° | 66° | 70° | 68° | 60° | 51° | 44° |
The curve peaks near 70°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with Medford's pool season and Salem's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Oregon season index.
Portland pool season FAQ
When should I open my pool in Portland, OR?
Open by May 18 — the model places Portland's 61°F crossing about two weeks later, and every warm day you wait pushes the water toward the 65°F algae zone. The Portland opening guide has the 12-step sequence.
When should I close my pool in Portland?
Close by October 10: cool water keeps its winter chemistry, but freeze damage is the hard stop. The Portland closing guide sequences the work backward from that date.
How long is the swim season in Portland?
Portland averages 40 days a year with normal highs of 80°F or better — about 6 days earlier than the Oregon median. The Oregon season index ranks all 8 covered cities by the same metric.
How warm does pool water get in Portland?
An unheated pool near Portland typically peaks around 70°F in high summer and bottoms out near 41°F in winter, never quite reaching the 78°F comfort line without a heater or solar cover. The month-by-month curve above shows the whole cycle; the methodology page explains the ±5°F error bars.
Email me when Portland hits the closing window
Data: NOAA 1991–2020 climate normals via Portland Kgw-tv (2.3 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.