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

 

 

Other Notable September 2009 High Temps: 

96ºF in Aguadilla on September 3rd
95ºF in Gurabo on September 27th  
95ºF in Corozal on September 13th
95ºF in Rio Piedras on September 29th              
95ºF at Dos Bocas on September 29th
94ºF in Magueyes, Levittown, San Juan, Juncos and Guayama

Other Notable September 2009 Low Temps:

62ºF in Toro Negro on September 5th & 18th   
62ºF in Trujillo Alto on September 26th   
64ºF in Aibonito on September 6th   
67ºF in Arecibo on September 14th
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 5th of the month. The highest weekly rainfall total occurred in Trujillo Alto, where 9.39” of rainfall accumulated the week ending September 18th. 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 9th & 17th       
74ºF – September 5th
Saint Thomas
93ºF – September 1st  
 
71ºF – September 5th
Saint Croix
91ºF – September 1st & 2nd
74ºF – September 5th

 
September Historical Statistics:
 
Highest September Temperatures on record:
 

San Juan              
97ºF – September 1st, 1981
96ºF – September 18th, 1995
*Most recent occurrence  
Saint Thomas      
98ºF – September 1st, 5th & 28th, 1993
97ºF – September 5th, 1995*
*Most recent occurrence
Saint Croix
95ºF – September 14th, 1983 & September 12th, 15th, 18th & 25th, 1972
94ºF – September 18th, 1983*
*Most recent occurrence

 
Lowest September Temperatures on record:
 

San Juan              
69ºF – September 15th, 1960
70ºF – September 9th, 1988*
*Most recent occurrence
Saint Thomas
68ºF – September 11th, 1994, September 9th, 1979 & September 11th & 20th, 1972
69ºF – September 9th, 1980
Saint Croix
63ºF – September 5th, 1979
67ºF – September 5th, 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 1st, 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 1st 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 31st, 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 1st 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 4th of the month at 2:10 am AST. There will also be a new moon on the 25th of the month at 8:42 pm AST. The first quarter of the moon was observed on the 26th of September and the last quarter of the moon will be observed on the 11th 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.

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