Pool season · State index
Idaho Pool Season 2026: Opening & Closing Dates by City
Last updated: July 25, 2026 · 5 cities covered
Both halves of the pool year for all 5 covered Idaho cities. The median calendar runs May 9 to October 3. Every row links to a one-page season overview with the live water-temperature model; the opening and closing hubs carry the full checklists.
Idaho: a short-season pool state| City | Open by | Close by | 80°F+ days |
|---|---|---|---|
| Boise | May 6 | Oct 9 | 96 |
| Coeur d'Alene | Jun 1 | Sep 26 | 53 |
| Idaho Falls | May 27 | Sep 23 | 70 |
| Meridian | May 6 | Oct 9 | 96 |
| Nampa | May 9 | Oct 3 | 103 |
What the columns mean
"Open by" is the recommended spring date — two weeks before the city's 7-day mean temperature crosses 61°F, the model's proxy for water approaching the 65°F algae-growth zone. "Close by" is the fall deadline — ten days after the water leaves that zone, capped a week ahead of the local 50% first-freeze date. "80°F+ days" counts days whose normal high reaches 80°F: the length of the true warm-swim season, and the fairest single number for comparing Idaho cities against each other.
Every figure comes from each city's own NOAA 1991–2020 normals station (named in its guide's footer), so neighboring cities can legitimately differ by a few days. The season overview linked from each row adds the live water-temperature model and the full-year season bar; the state hubs above carry the step-by-step checklists.
Swim-season length across Idaho
The fairest way to compare Idaho cities is the number of days with 80°F+ normal highs — the practical warm-swim season. Every bar links to that city's one-page season overview with the live water model.
Idaho pool climate at a glance
Mountain terrain and long, snowy winters compress Idaho's season into high summer, though the lower Snake River Plain around Boise warms earlier than the high country. In model terms that makes Idaho a short-season state. The spread shows up clearly on the local pages: compare Nampa's pool season with Meridian's and the difference is measured in weeks, not days. Neighbors in the index run on their own normals too — see Hawaii and Illinois for the adjacent calendars.
Idaho pool season FAQ
When do pools open in Idaho?
Model openings in Idaho run from May 6 in Boise to June 1 in Coeur d'Alene, with the statewide median on May 9. Each date is two weeks before that city's 7-day mean temperature crosses 61°F — early enough to start up in algae-cold water.
When should you close a pool in Idaho?
The median Idaho closing deadline is October 3, and every city's own deadline is capped a week ahead of its NOAA 50% first-freeze date. Closing late and cold beats closing early and warm — cool water holds its winter chemistry far better.
Which Idaho city has the longest swim season?
Nampa leads with 103 days of 80°F+ highs per year, while Coeur d'Alene brings up the rear at 53 days. The chart above ranks every covered city by the same metric.