Pool season · Indiana
Bloomington Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
One bar, one year, one Bloomington 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.
Bloomington, IN — 98 swim days a yearReading it takes ten seconds: 52 dots, one per week. Solid teal is Bloomington's swim season; the hollow teal run before it (April 18 to May 9) is when to open; the hollow amber run after is when to close, with October 11 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.
The Bloomington pool calendar
Opening — target April 25
Target April 25; the practical window runs April 18–May 9, and the 7-day mean crosses the 61°F threshold around May 9. Cold-water starts are the cheap ones.
Closing — deadline October 11
Hold the cover until October 1, then winterize by October 11, a week ahead of the October 26 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
This is Bloomington'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 30° | 30° | 38° | 48° | 59° | 68° | 74° | 75° | 71° | 61° | 49° | 38° |
The curve peaks near 75°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with Anderson's pool season and Carmel's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Indiana season index.
Bloomington pool season FAQ
When should I open my pool in Bloomington, IN?
Target April 25. That date backs off two weeks from the day Bloomington's 7-day mean temperature reaches 61°F, so you start up in cold, algae-resistant water. Work the full checklist in the Bloomington opening guide.
When should I close my pool in Bloomington?
The closing deadline is October 11 — late enough that the water has cooled out of the algae zone, early enough to beat Bloomington's first-freeze normal by about a week. See the Bloomington closing guide for the winterizing steps.
How long is the swim season in Bloomington?
Bloomington averages 98 days a year with normal highs of 80°F or better — about 6 days earlier than the Indiana median. The Indiana season index ranks all 13 covered cities by the same metric.
How warm does pool water get in Bloomington?
An unheated pool near Bloomington typically peaks around 75°F in high summer and bottoms out near 29°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 Bloomington hits the closing window
Data: NOAA 1991–2020 climate normals via Bloomington Indiana University (0.7 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.