September 2009 Climate Report

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

September 2009 Highlights:

Temperatures across Puerto Rico ranged from 55ºF in Adjuntas on the 19^th of September to 98ºF in Ponce on the 3^rd of the month. Temperatures across the U.S. Virgin Islands ranged from 71ºF, September 5^th, at the Charlotte Amalie Airport on Saint Thomas, to 93ºF, also at the Charlotte Amalie Airport on Saint Thomas, observed on the 1^st of the month. Other notable temperatures for September 2009 are listed below:

Other Notable September 2009 High Temps:

96ºF in Aguadilla on September 3^rd

95ºF in Gurabo on September 27^th

95ºF in Corozal on September 13^th

95ºF in Rio Piedras on September 29^th

95ºF at Dos Bocas on September 29^th

94ºF in Magueyes, Levittown, San Juan, Juncos and Guayama

Other Notable September 2009 Low Temps:

62ºF in Toro Negro on September 5^th & 18^th

62ºF in Trujillo Alto on September 26^th

64ºF in Aibonito on September 6^th

67ºF in Arecibo on September 14^th

68ºF in Maricao, Gurabo and Ponce

The highest 24-hour precipitation total for the month of September was 4.73”, which fell at Santa Rita on the 5^th of the month. The highest weekly rainfall total occurred in Trujillo Alto, where 9.39” of rainfall accumulated the week ending September 18^th. While just over three inches of rain fell on Saint Croix during the month of September, mostly associated with Tropical Depression Erika, the 3.05” inches that accumulated was not enough to prevent the first 9 months of 2009 from continuing to mark the driest start to a year on record across the island.

Figure 1A – Island wide precipitation forJanuarySeptember2009

Figure 1B – Graphical Display of September2009 precipitation across Puerto Rico and the U.S. Virgin Islands derived from a combination of rain gage and radar data.

Monthly Weather Summary:

September 2009 Statistics:

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

5.34”

Saint Croix

89.2ºF

76.8ºF

83.0ºF

5.36”

September 2009 Observations:

High:

Low:

AvgT:

Pcpn:

San Juan

89.5ºF (+1.7ºF)

78.9ºF (+2.4ºF)

84.2ºF (+2.0ºF)

6.43” (0.83”)

Saint Thomas

87.9ºF (-2.3ºF)

78.5ºF (+1.6ºF)

83.2ºF (-0.4ºF)

5.04” (-0.30”)

Saint Croix

88.4ºF (-0.8ºF)

77.5ºF (+0.7ºF)

83.0ºF (-0.0ºF)

3.05” (-2.31”)

September 2009 Extremes:

High:

Low:

San Juan

94ºF – September 9^th & 17th

74ºF – September 5^th

Saint Thomas

93ºF – September 1^st

71ºF – September 5^th

Saint Croix

91ºF – September 1^st & 2^nd

74ºF – September 5^th

September Historical Statistics:

Highest September Temperatures on record:

San Juan

97ºF – September 1^st, 1981

96ºF – September 18^th, 1995

*Most recent occurrence

Saint Thomas

98ºF – September 1^st, 5^th & 28^th, 1993

97ºF – September 5^th, 1995*

*Most recent occurrence

Saint Croix

95ºF – September 14^th, 1983 & September 12^th, 15^th, 18^th & 25^th, 1972

94ºF – September 18^th, 1983*

*Most recent occurrence

Lowest September Temperatures on record:

San Juan

69ºF – September 15^th, 1960

70ºF – September 9^th, 1988*

*Most recent occurrence

Saint Thomas

68ºF – September 11^th, 1994, September 9^th, 1979 & September 11^th & 20^th, 1972

69ºF – September 9^th, 1980

Saint Croix

63ºF – September 5^th, 1979

67ºF – September 5^th, 1954

Wettest Septembers:

San Juan

15.15” September 1996

14.83” September 1989

11.44” September 1976

Saint Thomas

14.94” September 1953

13.89” September 2004

12.86” September 2008

Saint Croix

21.39” September 1979

19.15” September 1996

9.80” September 1953

Driest Septembers:

San Juan

1.73” September 1987

1.78” September 2006

1.93” September 1961

Saint Thomas

1.08” September 1986

1.42” September 1987

1.62” September 1983

Saint Croix

1.07” September 1981

1.64” September 2001

1.96” September 1986

2000-2009 Decade in Review:

Decadal Observations for San Juan, Puerto Rico:

Decadal September High Temperatures:

2000’s		1990’s		1980’s		1970’s		1960’s		1950’s*
*89.2ºF*		*89.3ºF*		*89.9ºF*		*88.4ºF*		*87.8ºF*		*88.4ºF*

Decadal September Low Temperatures:

2000’s		1990’s		1980’s		1970’s		1960’s		1950’s*
*77.2ºF*		*76.9ºF*		*76.6ºF*		*76.9ºF*		*74.9ºF*		*73.6ºF*

Decadal September Average Temperatures:

2000’s		1990’s		1980’s		1970’s		1960’s		1950’s*
*83.2ºF*		*83.1ºF*		*83.2ºF*		*82.7ºF*		*81.4ºF*		*81.0ºF*

Decadal September Precipitation:

2000’s		1990’s		1980’s		1970’s		1960’s		1950’s*
*5.86”*		*6.44”*		*4.61”*		*6.02”*		*5.83”*		*5.02”*

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

Figure 2 – Temperature deviations for San Juan, PR

Figure 3 – Temperature deviations for Saint Thomas, VI

Figure 4 – Temperature deviations for Saint Croix, VI

Figure 5 – September precipitation deviations 2000s

Figure 6 – Year-to-Date precipitation deviations for San Juan, Saint Thomas, and Saint Croix

Looking ahead toward the month of October:

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

High:

Low:

AvgT:

Pcpn:

San Juan

87.5ºF

75.6ºF

81.6ºF

5.06”

Saint Thomas

89.5ºF

76.2ºF

82.9ºF

5.57”

Saint Croix

88.5ºF

75.9ºF

82.2ºF

5.22”

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

The sun rises at 6:15 am AST on the 1^st of October and sets at 6:13 pm AST, in San Juan, Puerto Rico. This represents a total of 11 hours and 58 minutes of daylight. By October 31^st, the sun will rise at 6:24 am AST and set at 5:52 pm AST, providing a total of 11 hours and 28 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 6:10 am AST and set at 6:08 pm AST on the 1^st of the month. By the end of the month, the sun will rise at 6:19 am AST and set at 5:47 pm AST, representing a total decrease in daylight of 30 minutes for the month.

For the month of October, a full moon will be observed on the 4^th of the month at 2:10 am AST. There will also be a new moon on the 25^th of the month at 8:42 pm AST. The first quarter of the moon was observed on the 26^th of September and the last quarter of the moon will be observed on the 11^th of October.

Links to additional sunrise/sunset data, phases of the moon, sunrise/sunset data 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