Pool season · Arizona
Tempe Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
One bar, one year, one Tempe 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.
Tempe, AZ — 245 swim days a yearEach dot on the bar is one week of Tempe's typical year, colored by what the model says that week is for: gray weeks are off-season, hollow teal marks the opening window (February 13–March 6), solid teal is swim season, and hollow amber is the closing window ending November 28. The black marker is today — its position against the colors is the entire executive summary.
The Tempe pool calendar
Opening — target February 20
Target February 20; the practical window runs February 13–March 6, and the 7-day mean crosses the 61°F threshold around March 6. Cold-water starts are the cheap ones.
Closing — deadline November 28
The window opens November 18 once water leaves the algae zone; the model deadline is November 28, a week ahead of the December 5 freeze normal.
Estimated water temperature by month
This is Tempe'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 54° | 56° | 60° | 66° | 73° | 82° | 89° | 91° | 88° | 79° | 68° | 57° |
Warmest water typically June–October (peaking near 91°F); heaters and covers shift any month up.
Every station tells its own story: compare this curve with Surprise's pool season and Tucson's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Arizona season index.
Tempe pool season FAQ
When should I open my pool in Tempe, AZ?
Target February 20. That date backs off two weeks from the day Tempe's 7-day mean temperature reaches 61°F, so you start up in cold, algae-resistant water. Work the full checklist in the Tempe opening guide.
When should I close my pool in Tempe?
The closing deadline is November 28 — late enough that the water has cooled out of the algae zone, early enough to beat Tempe's first-freeze normal by about a week. See the Tempe closing guide for the winterizing steps.
How long is the swim season in Tempe?
Tempe averages 245 days a year with normal highs of 80°F or better — about 5 days earlier than the Arizona median. The Arizona season index ranks all 20 covered cities by the same metric.
How warm does pool water get in Tempe?
An unheated pool near Tempe typically peaks around 91°F in high summer and bottoms out near 53°F in winter, spending roughly 5 months at or above the 78°F comfort line most swimmers prefer. The month-by-month curve above shows the whole cycle; the methodology page explains the ±5°F error bars.
Email me when Tempe hits the closing window
Data: NOAA 1991–2020 climate normals via Tempe ASU (2.7 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.