Pool season · Massachusetts
Lowell Pool Season: the Year on One Bar
Last updated: July 15, 2026 · dates · water temp
One bar, one year, one Lowell 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.
Each dot on the bar is one week of Lowell'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 8–May 29), solid teal is swim season, and hollow amber is the closing window ending October 2. The black marker is today — its position against the colors is the entire executive summary.
The Lowell pool calendar
Opening — target May 15
Open by May 15 — a two-week head start on the May 29 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline October 2
Hold the cover until September 22, then winterize by October 2, a week ahead of the October 10 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
This is Lowell's typical-year water curve: the same EWMA model as the live widget, run on the 1991–2020 normals instead of this week's weather.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 27° | 25° | 31° | 41° | 53° | 63° | 71° | 72° | 68° | 57° | 45° | 35° |
The curve peaks near 73°F — comfortable-water months here usually involve a heater or a solar cover.
Email me when Lowell hits the closing window
Data: NOAA 1991–2020 climate normals via Lowell (2.1 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.