August 2009 Climate Report

August 2009 Climate Report for Puerto Rico and the U.S. Virgin Islands

August 2009 Highlights:

Temperatures across Puerto Rico ranged from 56ºF in Adjuntas on the 17^th of August to 97ºF in Ponce on the 10^th of the month. Temperatures across the U.S. Virgin Islands ranged from 70ºF at Beth Upper New Works on Saint Croix, observed both on August 3^rd & 30^th, to 93ºF, recorded at the airports on Saint Thomas and Saint Croix, on the 7^th & 8^th of the month respectively. Other notable temperatures for August 2009 are listed below:

Other Notable August 2009 High Temps:

96ºF in Aguadilla on August 30^th

95ºF in San Juan on August 26^th

95ºF at Dos Bocas on August 27^th

94ºF in Aguirre Central, Mayaguez, Lajas,

Guayama, and Gurabo.

Other Notable August 2009 Low Temps:

64ºF in Toro Negro on August 11^th

65ºF in Aibonito on August 18^th

65ºF in Maricao on August 25^th

67ºF in Lajas on August 17^th

67ºF in Arecibo on August 6^th

The highest 24-hour precipitation total for the month of August was 3.02”, which fell in Toro Negro on the 11^th of the month. The highest weekly rainfall total occurred in Rio Piedras, where 6.98” of rainfall accumulated the week ending August 7^th. Across the U.S. Virgin Islands, the island of Saint Croix recorded its third driest August on record, making the first 8 months of the year the driest start on record across the island.

Figure 1A – Island wide precipitation forJanuary-August2009

Figure 1B – Graphical Display of August 2009 precipitation across Puerto Rico and the U.S. Virgin Islands derived from a combination of rain gage and radar data.

Monthly Weather Summary:

August 2009 Statistics:

Average August Temperatures/Precipitation (NCDC 1971-2000 averages):

High:

Low:

AvgT:

Pcpn:

San Juan

87.8ºF

77.0ºF

82.4ºF

5.22”

Saint Thomas

90.8ºF

77.7ºF

84.3ºF

3.50”

Saint Croix

89.7ºF

77.9ºF

83.8ºF

3.81”

August 2009 Observations:

High:

Low:

AvgT:

Pcpn:

San Juan

89.9ºF (+2.1ºF)

78.9ºF (+1.9ºF)

84.4ºF (+2.0ºF)

8.57” (3.35”)

Saint Thomas

89.9ºF (-0.9ºF)

79.6ºF (+1.9ºF)

84.7ºF (+0.4ºF)

1.76” (-1.74”)

Saint Croix

90.0ºF (+0.3ºF)

78.7ºF (+0.8ºF)

84.4ºF (+0.6ºF)

1.66” (-2.15”)

August 2009 Extremes:

High:

Low:

San Juan

95ºF – August 26^th

76ºF – August 29^th

Saint Thomas

93ºF – August 7^th & 14^th

76ºF – August 17^th

Saint Croix

93ºF – August 8^th

75ºF – August 15^th & 20^th

August Historical Statistics:

Highest August Temperatures on record:

San Juan

97ºF – August 21^st, 1980

96ºF – August 10^th, 1980*

*Most recent occurrence

Saint Thomas

99ºF – August 4^th, 1994 & August 8^th, 1979

98ºF – August 13^th, 1994*

*Most recent occurrence

Saint Croix

95ºF – August 25^th, 1999 & August 19^th, 1972

94ºF – August 4^th, 1972*

*Most recent occurrence

Lowest August Temperatures on record:

San Juan

70ºF – August 24^th& 26^th, 1956

71ºF – August 23^rd, 2000*

*Most recent occurrence

Saint Thomas

67ºF – August 12^th, 1956

70ºF – August 18^th, 1982*

*Most recent occurrence

Saint Croix

63ºF – August 17^th, 1978

67ºF – August 31^st, 1979*

*Most recent occurrence

Wettest Augusts:

San Juan

11.31” August 1988

9.52” August 2000

9.38” August 1979

Saint Thomas

8.54” August 1963

8.22” August 2005

6.71” August 1955

Saint Croix

11.41” August 1979

11.04” August 1989

7.80” August 1978

Driest Augusts:

San Juan

1.83” August 1994

1.93” August 1982

1.94” August 1991

Saint Thomas

0.70” August 1993

0.98” August 1991

1.26” August 2002

Saint Croix

1.35” August 2005

1.40” August 1980

1.51” August 2009

2000-2009 Decade in Review:

Decadal Observations for San Juan, Puerto Rico:

Decadal August High Temperatures:

2000’s		1990’s		1980’s		1970’s		1960’s		1950’s*
*89.0ºF*		*89.4ºF*		*89.9ºF*		*88.3ºF*		*87.8ºF*		*88.1ºF*

Decadal August Low Temperatures:

2000’s		1990’s		1980’s		1970’s		1960’s		1950’s*
*77.6ºF*		*77.3ºF*		*77.0ºF*		*77.3ºF*		*75.6ºF*		*74.1ºF*

Decadal August Average Temperatures:

2000’s		1990’s		1980’s		1970’s		1960’s		1950’s*
*83.3ºF*		*83.3ºF*		*83.4ºF*		*82.8ºF*		*81.6ºF*		*81.1ºF*

Decadal August Precipitation:

2000’s		1990’s		1980’s		1970’s		1960’s		1950’s*
*5.92”*		*4.83”*		*5.08”*		*5.27”*		*6.13”*		*6.45”*

* Records for San Juan began on January 1^st, 1956

Looking ahead toward the month of September:

Average September Temperatures/Precipitation (NCDC 1971-2000 averages):

High:

Low:

AvgT:

Pcpn:

San Juan

87.8ºF

76.5ºF

82.2ºF

5.60”

Saint Thomas

90.2ºF

76.9ºF

83.6ºF

5.57”

Saint Croix

89.2ºF

76.8ºF

83.0ºF

5.36”

Moon/Sun/Tide Data for the month of September:

The sun rises at 6:10 am AST on the 1^st of September and sets at 6:39 pm AST, in San Juan, Puerto Rico. This represents a total of 12 hours and 29 minutes of daylight. By September 30^th, the sun will rise at 6:15 am AST and set at 6:14 pm AST, providing a total of 11 hours and 59 minutes of daylight, or a total decrease of 30 minutes over the course of the month. At Charlotte Amalie on Saint Thomas, the sun will rise at 6:05 am AST and set at 6:34 pm AST on the 1^st of the month. By the end of the month, the sun will rise at 6:10 am AST and set at 6:09 pm AST, also representing a total decrease in daylight of 30 minutes for the month.

For the month of September, a full moon will be observed on the 4^th of the month at 12:03 pm AST. There will also be a new moon on the 18^th of the month at 4:44 pm AST. The first quarter of the moon was observed on the 27^th of August and the last quarter of the moon will be observed on the 11^th of September.

Links to additional sunrise/sunset data, phases of the moon, as well as tide data can all be found by clicking on the climate link of the National Weather Service San Juan homepage (www.srh.noaa.gov/sju) and then clicking on the Astronomical tab.

National Weather Service Weather Forecast Office