Pool season · Massachusetts
Lowell Pool Season: the Year on One Bar
Last updated: July 25, 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.
Lowell, MA — 78 swim days a yearEach 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.
Every station tells its own story: compare this curve with Leominster's pool season and Lynn's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Massachusetts season index.
Lowell pool season FAQ
When should I open my pool in Lowell, MA?
Target May 15. That date backs off two weeks from the day Lowell's 7-day mean temperature reaches 61°F, so you start up in cold, algae-resistant water. Work the full checklist in the Lowell opening guide.
When should I close my pool in Lowell?
The closing deadline is October 2 — late enough that the water has cooled out of the algae zone, early enough to beat Lowell's first-freeze normal by about a week. See the Lowell closing guide for the winterizing steps.
How long is the swim season in Lowell?
Lowell averages 78 days a year with normal highs of 80°F or better — right on the statewide median. The Massachusetts season index ranks all 14 covered cities by the same metric.
How warm does pool water get in Lowell?
An unheated pool near Lowell typically peaks around 73°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 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.