Pool season · Maryland
Ellicott City Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
One bar, one year, one Ellicott City 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.
Ellicott City, MD — 89 swim days a yearReading it takes ten seconds: 52 dots, one per week. Solid teal is Ellicott City's swim season; the hollow teal run before it (April 13 to May 4) is when to open; the hollow amber run after is when to close, with October 15 as the deadline; gray is the covered season. Today's marker shows where you stand in that cycle right now.
The Ellicott City pool calendar
Opening — target April 20
Open by April 20 — a two-week head start on the May 4 crossing keeps startup chemistry small and beats the local service rush.
Closing — deadline October 15
The window opens October 5 once water leaves the algae zone; the model deadline is October 15, a week ahead of the November 7 freeze normal.
Estimated water temperature by month
This is Ellicott City'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 36° | 35° | 41° | 50° | 60° | 69° | 77° | 77° | 72° | 63° | 52° | 43° |
The curve peaks near 78°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with Columbia's pool season and Frederick's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Maryland season index.
Ellicott City pool season FAQ
When should I open my pool in Ellicott City, MD?
The site model recommends opening by April 20 — about two weeks before Ellicott City'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 Ellicott City opening guide.
When should I close my pool in Ellicott City?
Winterize by October 15. The model holds the deadline a week ahead of Ellicott City's NOAA 50% first-freeze date, so the plumbing is protected before the first hard night. The full sequence is in the Ellicott City closing guide.
How long is the swim season in Ellicott City?
Ellicott City averages 89 days a year with normal highs of 80°F or better — right on the statewide median. The Maryland season index ranks all 9 covered cities by the same metric.
How warm does pool water get in Ellicott City?
An unheated pool near Ellicott City typically peaks around 78°F in high summer and bottoms out near 35°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 Ellicott City hits the closing window
Data: NOAA 1991–2020 climate normals via Cylburn (11.0 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.