Pool season · Illinois
Waukegan Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
Waukegan'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.
Waukegan, IL — 48 swim days a yearReading it takes ten seconds: 52 dots, one per week. Solid teal is Waukegan's swim season; the hollow teal run before it (May 7 to May 28) is when to open; the hollow amber run after is when to close, with October 3 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.
The Waukegan pool calendar
Opening — target May 14
Target May 14; the practical window runs May 7–May 28, and the 7-day mean crosses the 61°F threshold around May 28. Cold-water starts are the cheap ones.
Closing — deadline October 3
The window opens September 23 once water leaves the algae zone; the model deadline is October 3, a week ahead of the October 19 freeze normal.
Estimated water temperature by month
Monthly averages of the site's water model run on Waukegan'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 25° | 23° | 31° | 41° | 52° | 63° | 71° | 72° | 68° | 58° | 46° | 33° |
The curve peaks near 72°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with Springfield's pool season and Alton's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Illinois season index.
Waukegan pool season FAQ
When should I open my pool in Waukegan, IL?
Open by May 14 — the model places Waukegan's 61°F crossing about two weeks later, and every warm day you wait pushes the water toward the 65°F algae zone. The Waukegan opening guide has the 12-step sequence.
When should I close my pool in Waukegan?
Close by October 3: cool water keeps its winter chemistry, but freeze damage is the hard stop. The Waukegan closing guide sequences the work backward from that date.
How long is the swim season in Waukegan?
Waukegan averages 48 days a year with normal highs of 80°F or better — about 9 days later than the Illinois median. The Illinois season index ranks all 18 covered cities by the same metric.
How warm does pool water get in Waukegan?
An unheated pool near Waukegan typically peaks around 72°F in high summer and bottoms out near 22°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 Waukegan hits the closing window
Data: NOAA 1991–2020 climate normals via Waukegan (1.6 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.