Pool season · Illinois
Evanston Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
One bar, one year, one Evanston 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.
Evanston, IL — 73 swim days a yearEach dot on the bar is one week of Evanston's typical year, colored by what the model says that week is for: gray weeks are off-season, hollow teal marks the opening window (May 5–May 26), solid teal is swim season, and hollow amber is the closing window ending October 5. The black marker is today — its position against the colors is the entire executive summary.
The Evanston pool calendar
Opening — target May 12
Open by May 12 — a two-week head start on the May 26 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline October 5
Hold the cover until September 25, then winterize by October 5, a week ahead of the October 21 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
Monthly averages of the site's water model run on Evanston'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 26° | 25° | 33° | 43° | 53° | 64° | 72° | 73° | 69° | 59° | 46° | 35° |
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 Elgin's pool season and Joliet's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Illinois season index.
Evanston pool season FAQ
When should I open my pool in Evanston, IL?
The site model recommends opening by May 12 — about two weeks before Evanston'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 Evanston opening guide.
When should I close my pool in Evanston?
Winterize by October 5. The model holds the deadline a week ahead of Evanston's NOAA 50% first-freeze date, so the plumbing is protected before the first hard night. The full sequence is in the Evanston closing guide.
How long is the swim season in Evanston?
Evanston averages 73 days a year with normal highs of 80°F or better — about 7 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 Evanston?
An unheated pool near Evanston typically peaks around 74°F in high summer and bottoms out near 24°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 Evanston hits the closing window
Data: NOAA 1991–2020 climate normals via Chicago Botanic Garden (8.0 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.