Pool season · Illinois
Champaign Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
This is the one-page view of Champaign'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.
Champaign, IL — 102 swim days a yearThe bar compresses Champaign's whole pool year into one lane rope: gray floats for the off-season, hollow teal for the April 19–May 10 opening window, solid teal for swim weeks, hollow amber for the closing stretch that ends October 11. Wherever the today marker sits, the nearest color change is your next appointment.
The Champaign pool calendar
Opening — target April 26
Open by April 26 — a two-week head start on the May 10 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline October 11
The window opens October 1 once water leaves the algae zone; the model deadline is October 11, a week ahead of the October 24 freeze normal.
Estimated water temperature by month
Monthly averages of the site's water model run on Champaign'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 28° | 27° | 36° | 47° | 58° | 69° | 75° | 75° | 71° | 61° | 48° | 36° |
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 Bloomington's pool season and Chicago's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Illinois season index.
Champaign pool season FAQ
When should I open my pool in Champaign, IL?
The site model recommends opening by April 26 — about two weeks before Champaign's 7-day mean temperature crosses 61°F, while the water is still too cold for algae. The step-by-step sequence is in the Champaign opening guide.
When should I close my pool in Champaign?
Winterize by October 11. The model holds the deadline a week ahead of Champaign's NOAA 50% first-freeze date, so the plumbing is protected before the first hard night. The full sequence is in the Champaign closing guide.
How long is the swim season in Champaign?
Champaign averages 102 days a year with normal highs of 80°F or better — about 9 days earlier than the Illinois median. The Illinois season index ranks all 18 covered cities by the same metric.
How warm does pool water get in Champaign?
An unheated pool near Champaign typically peaks around 75°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 Champaign hits the closing window
Data: NOAA 1991–2020 climate normals via Champaign 3s (2.7 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.