90°
Scattered Showers And Thunderstorms
42%
31
Washington County, MD · Lake
Greenbrier State Park
21843 National Pike, Boonsboro, MD 21713
42-acre man-made freshwater lake with a white-sand swim beach on South Mountain northeast of Boonsboro. Popular with DC/Baltimore day-trippers, so MD DNR now requires advance reservations on weekends/holidays Memorial Day–Labor Day.
Today's Conditions
Skip the beach today.
Thunderstorms · NWS alert active · 42% rain
Full NWS forecast for This Afternoon
Scattered showers and thunderstorms. Some of the storms could be severe. Mostly cloudy, with a high near 90. Southwest wind around 12 mph, with gusts as high as 20 mph. Chance of precipitation is 40%. New rainfall amounts between a tenth and quarter of an inch possible.
Tonight
A chance of showers and thunderstorms before 2am. Some of the storms could be severe. Mostly cloudy, with a low around 70. West wind around 10 mph, with gusts as high as 18 mph. Chance of precipitation is 40%. New rainfall amounts between a quarter and half of an inch possible.
Weather
- 90°F air — hot — hydrate and seek shade
- 42% rain — rain likely at some point
Safety
- Thunderstorms — stay off the water when storms approach
- NWS alert active — air quality alert issued july 17 at 4:40pm edt by nws baltimore md/washington dc
30 /100
skip
41 Sunbathe
14 Walk
1 Fish
27 Photo
Best for sunbathing today
Weather alert in effect
Air Quality Alert issued July 17 at 4:40PM EDT by NWS Baltimore MD/Washington DC
Atmosphere
Air Temp
90°F
Light Rain
Wind
12 mph
SW
Rain
42%
This Afternoon
UV Peak
9 Very High
High 11 AM–03 PM · burn in ~22m
Burn-free before 09 AM & after 06 PM
Tomorrow
85°F
Mostly Sunny
Water
Water Temp
—
Next High Tide
11:05 PM
1.7 ft · in 2.1h
Water Quality
Clean
6 MPN/100mL · E. coli
USGS · sampled 10mo ago
Sun & Moon
Sunrise
5:57 AM
Sunset
8:35 PM
Moon · 18%
Waxing Crescent
Neap tides — smaller range
7-Day Beach Day Forecast
85°
Mostly Sunny
0%
84
85°
Mostly Sunny
3%
85
87°
Showers And Thunderstorms
81%
16
83°
Chance Rain Showers then Chance Showers And Thunderstorms
39%
37
80°
Slight Chance Rain Showers
15%
77
84°
Sunny
3%
85
What to Bring Today
- critical SPF 50 sunscreen UV index 9 — very high
- recommended Sturdy umbrella + sand anchor 12 mph wind
- optional Light cover-up, watch for pop-ups 42% rain chance
- critical Extra water / electrolytes 90°F - heat risk
- recommended Cooling towel or hat sustained heat
Always remember water bottle, trash bag (leave no trace).
Best Fishing Times Today
Solunar theory: fish activity peaks at moon transits (major) and moonrise/moonset (minor). All times local.
Minor
10:20 PM - 11:20 PM
Major
3:40 AM - 5:40 AM
Minor
10:20 AM - 11:20 AM
Major
4:00 PM - 6:00 PM
Beach Info
Parking
State park lot.
Dogs
Dogs permitted on leash in designated areas; not on swim beach.
Entry Fee
$3/person MD resident, $5/person out-of-state (May/Sep weekends); higher in-season. Advance day-use reservation required weekends & holidays Memorial Day–Labor Day.
Address
21843 National Pike, Boonsboro, MD 21713
Amenities
Frequently Asked
Is it safe to swim at Greenbrier State Park today?
Greenbrier State Park shows a live water-quality reading (bacteria levels) and today's swim-safety score at the top of this page, refreshed on every update. Seasonal lifeguards patrol the swim area in summer — follow their flags. Always review the current advisories, surf, and rip-current notes before getting in the water.
Is Greenbrier State Park dog-friendly?
Dogs permitted on leash in designated areas; not on swim beach.
Is there an entry fee at Greenbrier State Park?
$3/person MD resident, $5/person out-of-state (May/Sep weekends); higher in-season. Advance day-use reservation required weekends & holidays Memorial Day–Labor Day.
Are there lifeguards at Greenbrier State Park?
Yes. Seasonal lifeguards patrol Greenbrier State Park during the summer swim season (typically Memorial Day through Labor Day). Outside that window, swim at your own risk.
What amenities are at Greenbrier State Park?
Amenities at Greenbrier State Park include lifeguards, beach, camping, boat launch, boat rentals, fishing, trails, restrooms.
When is the water warmest at Greenbrier State Park?
Inland lakes peak in July and August at 75-80°F and hold warmth longer than tidal beaches. Swimming comfortable from mid-June through September.
Where is Greenbrier State Park located?
Greenbrier State Park is in Washington County, MD, at 21843 National Pike, Boonsboro, MD 21713.
Nearby Beaches
Updated · Data from NOAA, NWS