Pool season · Idaho
Boise Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
This is the one-page view of Boise's pool year: both model windows, the estimated water-temperature curve, and today's live position on the season bar. The detailed checklists live on the opening and closing guides; this page is the calendar you check between them.
The bar compresses Boise's whole pool year into one lane rope: gray floats for the off-season, hollow teal for the April 29–May 20 opening window, solid teal for swim weeks, hollow amber for the closing stretch that ends October 9. Wherever the today marker sits, the nearest color change is your next appointment.
The Boise pool calendar
Opening — target May 6
Target May 6; the practical window runs April 29–May 20, and the 7-day mean crosses the 61°F threshold around May 20. Cold-water starts are the cheap ones.
Closing — deadline October 9
The window opens September 29 once water leaves the algae zone; the model deadline is October 9, a week ahead of the October 21 freeze normal.
Estimated water temperature by month
This is Boise'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 31° | 34° | 42° | 48° | 56° | 64° | 73° | 78° | 71° | 60° | 46° | 35° |
Warmest water typically August–August (peaking near 79°F); heaters and covers shift any month up.
Email me when Boise hits the closing window
Data: NOAA 1991–2020 climate normals via Boise Air Terminal (2.4 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.