Pool season · Maryland
Baltimore Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
Baltimore'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.
Baltimore, MD — 110 swim days a yearThe bar compresses Baltimore's whole pool year into one lane rope: gray floats for the off-season, hollow teal for the April 5–April 26 opening window, solid teal for swim weeks, hollow amber for the closing stretch that ends October 24. Wherever the today marker sits, the nearest color change is your next appointment.
The Baltimore pool calendar
Opening — target April 12
Target April 12; the practical window runs April 5–April 26, and the 7-day mean crosses the 61°F threshold around April 26. Cold-water starts are the cheap ones.
Closing — deadline October 24
Hold the cover until October 14, then winterize by October 24, a week ahead of the November 21 freeze normal. Late and cold beats early and warm.
Estimated water temperature by month
Monthly averages of the site's water model run on Baltimore'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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 38° | 38° | 43° | 53° | 63° | 72° | 80° | 81° | 76° | 66° | 55° | 45° |
Warmest water typically July–August (peaking near 81°F); heaters and covers shift any month up.
Every station tells its own story: compare this curve with Waldorf's pool season and Columbia's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the Maryland season index.
Baltimore pool season FAQ
When should I open my pool in Baltimore, MD?
The site model recommends opening by April 12 — about two weeks before Baltimore'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 Baltimore opening guide.
When should I close my pool in Baltimore?
Winterize by October 24. The model holds the deadline a week ahead of Baltimore's NOAA 50% first-freeze date, so the plumbing is protected before the first hard night. The full sequence is in the Baltimore closing guide.
How long is the swim season in Baltimore?
Baltimore averages 110 days a year with normal highs of 80°F or better — about 8 days earlier than the Maryland median. The Maryland season index ranks all 9 covered cities by the same metric.
How warm does pool water get in Baltimore?
An unheated pool near Baltimore typically peaks around 81°F in high summer and bottoms out near 37°F in winter, spending roughly 2 months at or above the 78°F comfort line most swimmers prefer. The month-by-month curve above shows the whole cycle; the methodology page explains the ±5°F error bars.
Email me when Baltimore hits the closing window
Data: NOAA 1991–2020 climate normals via Md Sci Center Baltimore (1.7 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.