Marine Weather Net

Baltimore Harbor & Patapsco River Marine Forecast




5 - 10




10 - 15

The Marine Weather Forecast In Detail:
ANZ538 Forecast Issued: 434 AM EDT Wed Sep 28 2022

Rest Of The Overnight...W Winds 10 Kt. Waves 1 Ft.
Today...Nw Winds 5 To 10 Kt. Waves 1 Ft.
Tonight...N Winds 10 Kt With Gusts To 20 Kt. Waves 1 Ft.
Thu...N Winds 10 To 15 Kt With Gusts To 20 Kt. Waves 1 Ft.
Thu Night...Ne Winds 10 Kt. Waves 1 Ft.
Fri...Ne Winds 10 Kt. Waves 1 Ft.
Fri Night...Ne Winds 10 To 15 Kt With Gusts To 20 Kt. Waves 1 Ft. Rain Likely.
Sat...Ne Winds 10 To 15 Kt. Waves 1 Ft. Rain Likely.
Sun...Ne Winds 10 To 15 Kt. Waves 1 To 2 Ft. Rain Likely.
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Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
349am EDT Wednesday September 28 2022

An upper-level trough will remain overhead through tonight before moving off to the northeast Thursday. High pressure will build north of the area for later Thursday into Friday. Low pressure may impact the area this weekend into early next week. For the latest information on Ian, refer to the National Hurricane Center (

Near Term - Through Tonight
An upper-level trough will continue to build overhead while surface high pressure approaches from the north and west. A northwest flow will continue, and with the trough overhead it will be cool for this time of year. Max temps will range from the 40s and 50s in the Allegheny Highlands to the 60s and lower 70s for most other locations.

Most areas will be dry, but there will be some instability underneath a subsidence inversion, thanks to the upper-level trough. Scattered showers are expected in the Allegheny Highlands, especially late this morning into early this evening. A few isolated showers may spill east of the mountains into northern MD/eastern WV/northern VA this afternoon/early evening. An precipitation amounts will be light.

A sct/bkn cu deck will overspread the area from northwest to southeast this morning into this afternoon in response to the digging upper-level trough.

The trough will remain overhead tonight while high pressure continues to build toward the area. Dry and cool conditions are expected. A thin stratocu deck and light north to northwest wind should prevent any widespread frost from developing in the Allegheny Highlands.

Short Term - Thursday Through Friday Night
The upper-level trough will move away from the area Thursday while high pressure builds to the north. Dry conditions are expected along with some sunshine. Highs will be in the 60s to lower 70s for most areas (50s in the mountains). Dry and cool conditions will persist for Thursday night with high pressure nearby.

Ian will most likely track northward near the southeast coast Friday before moving further inland Friday night. Refer to the National Hurricane Center for the latest information regarding the track of Ian. Tropical moisture and warm air will overrun cooler air in place, resulting in increasing clouds Friday along with increasing chances for rain from southeast to northwest late Friday through Friday night.

Long Term - Saturday Through Tuesday
An increasingly likely wet start to the long term period as a result of future remnants from Hurricane Ian. Synoptically, a large area of high pressure over the Northeast will play a pivotal role in the progression of the incoming low pressure system to the south.

Should the latest forecast solution become realized, isolated instances of flooding as a result from moderate to heavy rainfall are possible, mainly south of the metropolitan areas where confidence is higher for heavier rainfall. Precedent dry soil conditions may be beneficial in this instance to relieving the flood threat to a more isolated nature. The rainfall will most likely hang around through Monday before slowly exiting toward the middle portion of next week.

With any complex system (i.e, a hurricane), uncertainties will remain heading closer to the actual event given the variability of the storms progression before reaching a point as well as other meso/micro/synoptic-scale forcing that may play a role. As always with any tropical events, please visit for the latest tropical forecast via the National Hurricane Center.

Temperatures for the long term will hover around at or just below average for most of the area in terms of highs (60s for most, 50s for higher elevations with localized 40s late in the weekend).

An SCA (Small Craft Advisory) is in effect for northwest winds over the middle portion of the Bay and middle/lower Tidal Potomac River. Winds should diminish by late this morning as the gradient subsides. However, the mixing layer will increase, so frequent gusts close to 15 knots are possible late this morning and afternoon. Guidance shows a weaker wind field aloft, so confidence is too low for an SCA (Small Craft Advisory) during this time.

A pressure surge is expected over the waters tonight, and an SCA is in effect for all of the waters except the upper Tidal Potomac River. The upper Tidal Potomac River may need to be added into the SCA, but confidence was too low at this time given the smaller fetch over those waters. The SCA (Small Craft Advisory) continues into Thursday afternoon.

The gradient between high pressure to the north and Ian approaching the southeastern CONUS will strengthen Thursday through Friday night, and an SCA (Small Craft Advisory) will likely be needed for at least portions of the waters during this time. Winds may even approach gale-force levels over the open waters south of North Beach late Friday night, but confidence is low at this time.

SCAs (Small Craft Advisories) are likely Saturday and Sunday for the waters. A low pressure system from the south will bring an increased pressure gradient. Gale-force winds are possible for the waters Saturday through early Monday, especially for the lower tidal Potomac River and the middle portion of the Chesapeake Bay. Confidence is low at this time with respect to potential Gale headlines given the variability for these winds 4 to 5 days out.

Tides / Coastal Flooding
An onshore flow will strengthen as high pressure remains to our north and low pressure tracks to the south. The persistent onshore flow will cause elevated tidal anomalies to develop Friday and continue through the weekend into early next week. Coastal flooding is possible during this time. Details remain highly uncertain depending on the exact track of Ian or its remnants. For the latest information on Ian, refer to the National Hurricane Center (

NOAA Baltimore MD/Washington DC Office: Watches - Warnings - Advisories
DC...None. MD...None. VA...None. WV...None.

Small Craft Advisory from 8pm this evening to 2pm EDT Thursday for ANZ530-531-536-538-539. Small Craft Advisory until 10am EDT this morning for ANZ531>534-536-537-539>541-543. Small Craft Advisory from 8pm this evening to 6pm EDT Thursday for ANZ532>534-537-540>543.