Marine Weather and Tide Forecast for Mount Vernon, VA

KEY MESSAGES
1) Above average temperatures are expected beginning this weekend along with daily shower and thunderstorm chances through Tuesday.

2) A more organized threat for severe thunderstorms is shaping up for Wednesday along a strong cold front.

DISCUSSION
KEY MESSAGE 1...Above average temperatures are expected beginning this weekend along with daily shower and thunderstorm chances through the middle of next week.

One more Spring-like day today before summertime heat settles in this weekend into the middle of next week. Upper level low pressure will push offshore today as high pressure builds in from the Ohio River Valley. With that said, expect more sunshine mixed in with mid and high level cloud cover. Breezy conditions will remain for the front half of the day given the gradient between the departing low and incoming high. Expect gusts between 20 to 25 mph gradually diminishing during the late afternoon and early evening hours. Highs today will push into the upper 60s and low 70s as a result of more sunshine. Winds go calm tonight with clear skies allowing temps to fall back into the 40s and low 50s.

High pressure will drift offshore Saturday into Sunday allowing for persistent return flow into the region. Meanwhile, heights will rise as broad high pressure strengthens offshore. At the same time, the upper level flow pattern becomes much more zonal allowing a front to try and drop south into the region. The stationary front over the Ohio River Valley and eastern Great Lakes will act as a catalyst for multiple pieces of upper level energy to pivot through.
These pieces of energy could help initiate a few spotty showers or t- storms mainly across the mountains on both Saturday and Sunday afternoons. Overall most of the weekend will remain dry with highs for most Saturday in the 80s and pushing 90 Sunday.

Upper-level ridging will continue to strengthen to our east Monday into Tuesday, while surface high pressure builds over the Central Atlantic. This will continue to pump hot and increasingly humid air into the region. As the ridge gradually shifts east however, that breakdown in the ridge from west to east across the forecast area may allow for a couple of storms to develop each day, especially west of the Blue Ridge. A strong thunderstorm can't be ruled out during this time in this type of airmass. The early runs of the RRFS that include Monday afternoon are quite aggressive with convection Monday afternoon West of the Blue Ridge, so am at least slightly more concerned with the severe threat that day than earlier today. However, will continue to monitor future model runs to see if this trend continues.

KEY MESSAGE 2...A more organized threat for severe thunderstorms is shaping up for Wednesday along a strong cold front.

A strong cold front will try to make its way through the region Wednesday into Wednesday night bringing us a higher chance of showers and thunderstorms. This activity will feed off of the higher humidity and heat. It will also of course be accompanied by a much higher amount of shear. This will result in a substantially higher severe weather threat compared to the earlier days in the week. Expecting storms to fire up along a pre-frontal trough ahead of the main cold front Wednesday afternoon/evening, and the the actual front would come through late evening/overnight.

This front then has the potential to retreat northward as a warm front Thursday afternoon and night. Temperatures will likely cool due to extra cloud cover and additional shower/t-storm chances across the region.

The front may remain nearby through Friday before clearing the area for the upcoming weekend as Canadian high pressure builds south from the Great Lakes region.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
VFR conditions are expected through the weekend into early next week. Expect pockets of mid and high level cloud cover to return through this evening before SKC conditions return late tonight into early Saturday morning. Gusty northwest winds will continue to diminish this afternoon as high pressure builds in from the Ohio River Valley.

Winds will go calm to variable overnight as the high settles nearby. High pressure drifts offshore Saturday into Sunday allowing winds to switch back to the south and southwest at less than 15 kts. VFR conditions will prevail with a shower or t- storm possibly approaching KMRB, KHGR, and KFDK late Saturday evening after 23z/7pm. Confidence in this is very low given residual dry air aloft.

Primarily VFR conditions are expected at terminals on Sunday and Monday. An isolated tstorm could affect the northern terminals Sunday (i.e MRB, HGR, FDK, IAD, BWI) that could cause temporary reduced conditions at terminals. Winds briefly shift westerly Sunday afternoon before shifting south southeast on Monday. Additional spotty t-storm chances are possible Tuesday mainly at MRB.

More widespread sub-VFR conditions are likely Wednesday and Thursday as a cold front pushes through. Storms could be strong to severe as this pushes through.

MARINE
SCAs continue for all waters through 4pm this afternoon, but winds are already starting to taper off. Sub-SCA level winds continue into Saturday morning as high pressure builds nearby.
Winds will become variable tonight before turning to the south Saturday. Occasional SCA conditions will be possible across portions of the waters due to south to southwesterly channeling Saturday, but confidence is too low for Small Craft Advisories at this time.

Winds drop back below SCA levels Sunday into Monday, although occasional gusts up to SCA level are possible in channeling over the open waters during this aforementioned time.
Southwesterly winds gradually become southeasterly Monday night.

No marine hazards expected Tuesday through Tuesday night.
Winds south to southwest 5 to 10 knots through the period.

Showers and storms associated with an approaching cold front will traverse the waters Wednesday afternoon. These will bring the chance for severe weather, so SMWs may be needed during this time.

CLIMATE
Here are some daily temperature records during the May 18-20, 2026 timeframe:

A '+' sign indicates multiple years currently hold that record.
A '!' sign indicates the record is forecast to be tied or broken.

***MONDAY, MAY 18TH, 2026*** LOCATION RECORD HIGH (YEAR) RECORD WARM LOW (YEAR)
Washington-National (DCA) 96F (1877) 72F (2015)
Washington-Dulles (IAD) 91F (1987)! 68F (2015)! Baltimore (BWI) 97F (1962) 70F (2017)
Baltimore Inner Harbor (DMH) 97F (1962) 75F (2017)
Martinsburg (MRB) 96F (1911) 66F (2015)! Charlottesville (CHO) 95F (1962)+ 73F (1911)
Annapolis (NAK) 95F (1962)+ 69F (1953)+! Hagerstown (HGR) 93F (1962) 71F (2017)

***TUESDAY, MAY 19TH, 2026*** LOCATION RECORD HIGH (YEAR) RECORD WARM LOW (YEAR)
Washington-National (DCA) 96F (1997)+ 72F (2015)! Washington-Dulles (IAD) 92F (1997)+! 66F (2017)+! Baltimore (BWI) 98F (1962) 75F (1877)
Baltimore Inner Harbor (DMH) 98F (1962) 78F (1962)
Martinsburg (MRB) 98F (1911) 69F (1996)! Charlottesville (CHO) 97F (1962) 72F (1997)
Annapolis (NAK) 96F (1962) 71F (1911)! Hagerstown (HGR) 97F (1996) 69F (2017)+!

***WEDNESDAY, MAY 20TH, 2026*** LOCATION RECORD HIGH (YEAR) RECORD WARM LOW (YEAR)
Washington-National (DCA) 96F (1996) 73F (2019)
Washington-Dulles (IAD) 93F (1996) 69F (2019)
Baltimore (BWI) 95F (1962) 71F (2019)+ Baltimore Inner Harbor (DMH) 97F (1962) 74F (1998)+ Martinsburg (MRB) 97F (1911) 70F (1998)
Charlottesville (CHO) 96F (1996) 73F (1996)
Annapolis (NAK) 98F (1997) 76F (1898)
Hagerstown (HGR) 97F (1996) 66F (1998)

LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 4 PM EDT this afternoon for ANZ530>543.