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Weather and Water Conditions for

32 Chesapeake Bay Swims

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Past Conditions

Links for Current Conditions:

Bay Water/Wind: Thomas Point Lighthouse (TPLH)
 Area Weather: Annapolis

Thomas Point Lighthouse is operated by the National Data Buoy Center, a part of the National Weather Service.  Since Thomas Point Lighthouse is located 8 miles south of the Chesapeake Bay Bridges (see map below), it is an excellent source of important information about the conditions that swimmers encounter during the Great Chesapeake Bay Swim (GCBS), especially the water temperature and wind magnitude and direction.

Start of GCBS:  
Finish of GCBS:  
Thomas Point Lighthouse:  

39:00:29N   76:24:08W
38:58:55N   76:20:06W
38:53:54N   76:26:12W

tplh.gif (20551 bytes)
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Previous Bay Swim Conditions

  Temp, (F) Wind
Year Water Air mph Direction
2017 72 73 8 SSE
2016 72 87 25 WNW
2015 77 80 8 S
2014 73 73 12 SSE
2013 71 71 7 NE
2012 74 78 3 N
2011 77 79 3 E
2010 74 74 9 S
2009 74 70 11 NE
2008 72 79 9 S
2007 75 69 6 E
2006 69 62 13 WNW
2005 75 75 13 SSE
2004 71 67 15 SSW
2003 64 63 4 NNE
2002 72 73 11 SW
2001 71 73 6 SE
2000 71 76 10 SSE
1999 71 69 15 NNE
1998 67 74 18 WNW
1997 63 60 9 NNE
1996 69 71 15 SSE
1995 73 77 12 SSE
1994 71 71 14 SSE
1993 72 66 9 ENE
1992 72 69 8 N
1991 71 71 9 N
1990 70 74 13 WNW
1989 70 63 19 WNW
1988 66 67 19 W
1987 71 70 6 SSE
1986 75 74 11 SSE

Key to Wind Direction

Wind
Direction

(WD)

Degrees clockwise from North

North

0

NNE

23

NE

45

ENE

68

East

90

ESE

113

SE

135

SSE

158

South

180

SSW

203

SW

225

WSW

248

West

270

WNW

293

NW

315

NNW

338

North

360


The above water, air, and wind conditions
were calculated from TPLH
Historical Data:

GCBS
Year
Sunday,
June
Start
Time
Thomas Point Lighthouse Measurements
(see definitions below)
Time* WD WSPD GST BAR ATMP WTMP
2017 11 8:30 AM 10:00 AM 160 3.6 3.6 1020.2 22.6 22.0
2016 12 12:15 PM 2:00 PM 290 11.3 11.8 1007.4 30.7 22.4
2015 14 12:15 PM 2:00 PM 180 3.6 4.1 1018.0 26.8 24.8
2014 8 10:30 AM noon 157 5.3 5.6 1015.0 23.0 22.8
2013 9 8:25 AM 10:00 AM 50 3.1 3.6 1023.0 21.8 21.9
2012 10 11:00 AM noon 350 1.5 3.1 1019.4 25.3 23.1
2011 12 11:30 AM 1:00 PM 80 1.2 1.5 1011.1 25.9 25.0
2010 13 8:00 AM 9:00 AM 177 3.9 4.7 1012.0 23.5 23.3
2009 14 10:20 AM noon 55 5.0 5.6 1015.6 21.3 23.5
2008 8 10:00 AM 11:00 AM 174 4.2 4.4 1016.4 25.9 22.1
2007 10 9:30 AM 11:00 AM 100 2.6 2.9 1017.0 20.6 23.8
2006 11 10:00 AM 11:00 AM 295 5.9 7.7 1011.8 16.5 20.7
2005 12 10:30 AM noon 160 5.8 6.2 1018.5 24.1 23.9
2004 13 9:30 AM 11:00 AM 198 6.7 7.5 1024.1 19.3 21.5
2003 8 12:30 PM 2:00 PM 22 1.8 2.1 1012.9 17.4 18.0
2002 16 11:00 AM noon 227 4.9 5.9 1009.0 22.7 22.0
2001 10 10:30 AM noon 140 2.6 2.6 1014.1 22.7 21.5
2000 11 9:45 AM 11:00 AM 168 4.5 4.7 1019.2 24.2 21.5
1999 13 7:15 AM 9:00 AM 31 6.8 7.5 1021.2 20.4 21.8
1998 14 10:50 AM noon 297 8.2 9.9 1001.7 23.2 19.5
1997 8 10:00 AM 11:00 AM 21 3.8 4.1 1021.6 15.8 17.3
1996 9 8:30 AM 10:00 AM 149 6.6 7.4 1019.3 21.8 20.5
1995 11 1:00 PM 2:00 PM 154 5.4 5.8 1012.7 24.7 22.7
1994 12 10:00 AM 11:00 AM 168 6.1 6.6 1018.9 21.7 21.6
1993 13 9:15 AM 11:00 AM 72 3.9 4.1 1024.7 18.8 22.1
1992 28 8:30 AM 10:00 AM 352 3.5 4.0 1015.1 20.4 22.1
1991 9 8:05 AM 9:00 AM 1 3.8 3.9 1022.0 21.8 21.7
1990 10 8:00 AM 9:00 AM 296 5.7 6.9 1011.9 23.3 21.1
1989 11 8:00 AM 9:00 AM 292 8.7 10.5 1021.0 17.3 21.2
1988 12 8:00 AM 9:00 AM 276 8.4 9.3 1020.0 19.6 18.8
1987 14 8:00 AM 9:00 AM 160 2.6 2.6 1013.2 21.2 21.4
1986 15 10:00 AM 11:00 AM 160 5.1 5.1 1019.7 23.2 23.8

Definitions
of standard meteorological data measurements:

ATMP     Air temperature (Celsius) at 17.4 meters above sea level
WTMP    Sea surface temperature (Celsius), F = 1.8(C) + 32
BAR        Sea level barometric pressure (mb), 100 mb = 29.53 inches of mercury
WSPD    Hourly average wind speed (m/s), 1 m/s = 2.237 mph = 1.9425 knots (US)
WD        Hourly average wind direction (degrees clockwise from North), see above
GST       Peak 8-sec. gust speed (m/s), RE: Beaufort Scale
Time      * Note:  In the NOAA Historical Data, Time (day, DD, and hour, hh) is provided in UTC or Universial Time.  To obtain Eastern Daylight-Saving Time, which is when the GCBS is held, 4 hours are substracted from the UTC.  The Time shown above is the corrected (actual) time at the bay bridges. The TPLH measurements shown occurred when most swimmers were in the middle of the event.