Pool season · Indiana
Indianapolis Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
Indianapolis'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.
Indianapolis, IN — 87 swim days a yearThe bar compresses Indianapolis's whole pool year into one lane rope: gray floats for the off-season, hollow teal for the April 21–May 12 opening window, solid teal for swim weeks, hollow amber for the closing stretch that ends October 8. Wherever the today marker sits, the nearest color change is your next appointment.
The Indianapolis pool calendar
Opening — target April 28
Open by April 28 — a two-week head start on the May 12 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline October 8
The window opens September 28 once water leaves the algae zone; the model deadline is October 8, a week ahead of the October 21 freeze normal.
Estimated water temperature by month
This is Indianapolis'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 28° | 28° | 36° | 46° | 58° | 68° | 74° | 74° | 70° | 60° | 47° | 36° |
The curve peaks near 74°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with Hammond's pool season and Lafayette's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Indiana season index.
Indianapolis pool season FAQ
When should I open my pool in Indianapolis, IN?
Target April 28. That date backs off two weeks from the day Indianapolis's 7-day mean temperature reaches 61°F, so you start up in cold, algae-resistant water. Work the full checklist in the Indianapolis opening guide.
When should I close my pool in Indianapolis?
The closing deadline is October 8 — late enough that the water has cooled out of the algae zone, early enough to beat Indianapolis's first-freeze normal by about a week. See the Indianapolis closing guide for the winterizing steps.
How long is the swim season in Indianapolis?
Indianapolis averages 87 days a year with normal highs of 80°F or better — right on the statewide median. The Indiana season index ranks all 13 covered cities by the same metric.
How warm does pool water get in Indianapolis?
An unheated pool near Indianapolis typically peaks around 74°F in high summer and bottoms out near 26°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 Indianapolis hits the closing window
Data: NOAA 1991–2020 climate normals via Indianapolis SE Side (5.9 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.