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Interactive vector navigation map with 6-frame NOAA NEXRAD Doppler precipitation loop, real-time 30-mile lightning strike proximity scope, verified public boat launch ramps, marinas, and USGS telemetry stations for St. Mary's Lake.
Landscape photo: Genbao Zhang (CC BY-SA 4.0) via Wikimedia Commons
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If the delay between seeing a lightning flash and hearing thunder is 30 seconds or less, the thunderstorm cell is within 6 miles — seek shelter immediately. Always wait a full 30 minutes after the last clap of thunder before returning to open water.
| Station Name | Provider | Site ID | Coordinates | Monitored Telemetry | Action |
|---|---|---|---|---|---|
| St Marys Lake near Callaway, MD | usgs | 01661499 | 38.2528° N, 76.5335° W | Gage Height, Elevation (NGVD 1929) | Inspect |
| St Marys River at Great Mills, MD | usgs | 01661500 | 38.2418° N, 76.5037° W | Discharge | Inspect |
| St Marys Lake near Callaway, MD | usgs | 01661499 | 38.2528° N, 76.5335° W | Gage Height, Elevation (NGVD 1929) | Inspect |
| St Marys River at Great Mills, MD | usgs | 01661500 | 38.2418° N, 76.5037° W | Discharge | Inspect |
St. Mary's Lake is located in Maryland at coordinates 38.2700° N, 76.5400° W. These coordinates represent the hydrographic center point verified against the USGS Geographic Names Information System (GNIS) and National Hydrography Dataset (NHD).
Our real-time lightning radar monitors electromagnetic atmospheric discharges within a 30-mile radius of St. Mary's Lake. Concentric safety rings indicate proximity: 5 miles (critical danger zone), 10 miles (15-minute arrival warning), 20 miles (basin caution), and 30 miles (perimeter monitoring). It tracks storm bearing, flash density, and evaluates the marine 30-30 safety rule.
The live radar overlay displays a real-time 6-frame precipitation loop powered by RainViewer and NOAA NEXRAD Doppler radar composites. It updates every 10 minutes to show incoming storms, rain, snow, and thunderstorm cells directly above St. Mary's Lake. You can pause, play, or scrub the timeline using the controls in the top-right corner of the map.
St. Mary's Lake features multiple shoreline access points. Launch sites typically provide concrete ramps, docks, and parking, though seasonal water levels and park permits may affect launch availability.
View All Cataloged Launch Sites on St. Mary's Lake →St. Mary's Lake has 4 mapped hydrological sensor stations. For continuous 30-day water level history, full-pool comparisons, and water temperature trends, check our dedicated water telemetry page.
View St. Mary's Lake Water Level & Temp Telemetry →Our Weather & Forecast page delivers 24-hour hour-by-hour wind timelines, peak gust forecasts, watercraft safety thresholds, and 7-day marine outlooks sourced directly from the National Weather Service.
Check St. Mary's Lake 24-Hour Wind & Weather Outlook →