Pool season · Massachusetts
Boston Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
Boston'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.
Each dot on the bar is one week of Boston'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 3–May 24), solid teal is swim season, and hollow amber is the closing window ending October 6. The black marker is today — its position against the colors is the entire executive summary.
The Boston pool calendar
Opening — target May 10
Open by May 10 — a two-week head start on the May 24 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline October 6
Hold the cover until September 26, then winterize by October 6, a week ahead of the October 23 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
Monthly averages of the site's water model run on Boston'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 30° | 29° | 34° | 43° | 54° | 64° | 73° | 74° | 70° | 59° | 48° | 38° |
The curve peaks near 74°F — comfortable-water months here usually involve a heater or a solar cover.
Email me when Boston hits the closing window
Data: NOAA 1991–2020 climate normals via Jamaica Plain (2.3 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.