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

July 2009 Highlights:

Temperatures across Puerto Rico ranged from 58ºF in Adjuntas on both the 10th and 25th of July to 100ºF in Corozal on the 12th of July. Temperatures across the U.S. Virgin Islands ranged from 67ºF at Beth Upper New Works on Saint Croix, observed July 21st, to 94ºF, also at Beth Upper New Works on Saint Croix, observed on July 20th. Other notable temperatures for July 2009 are listed below:
 

Other Notable July 2009 High Temps:             
 
97ºF in Ponce on July 30th   
96ºF in Aguadilla on July 3rd
96ºF in Mayaguez on July 28th
95ºF in Rio Piedras on July 14th         
94ºF in Rincon on July 8th
94ºF in Lajas on July 14th
 
Other Notable July 2009 Low Temps:
 
62ºF in Toro Negro on July 5th   
63ºF in Aibonito on July 22nd   
65ºF in Maricao on July 22nd   
66ºF in Lajas on July 1st & 21st   
67ºF in Arecibo on July 14th
 

 

The highest 24-hour precipitation total for the month of July was 5.09”, which fell in Jajome Alto on the 22nd of the month. The highest weekly rainfall total also occurred in Jajome Alto, where 6.85” of rainfall accumulated the week ending July 24th.

 

 

Figure 1A – Island wide precipitation forJanuary-July 2009

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

 

Monthly Weather Summary:
 
July 2009 Statistics:
 
Average July Temperatures/Precipitation (NCDC 1971-2000 averages):
 
 
High:     
Low:     
AvgT:   
Pcpn:      
San Juan              
87.4ºF
76.9ºF    
82.2ºF
4.16”
Saint Thomas
90.4ºF    
77.8ºF    
84.1ºF
2.42”
Saint Croix
89.3ºF
78.0ºF
83.7ºF
2.79”
 
July 2009 Observations:
 
 
High:     
Low:     
AvgT:   
Pcpn:      
San Juan
90.0ºF     (+2.6ºF)
79.5ºF     (+2.6ºF) 
84.8ºF     (+2.6ºF) 
4.80”       (0.64”)  
Saint Thomas
89.5ºF     (-0.9ºF)  
79.1ºF     (+1.3ºF) 
84.3ºF     (+0.2ºF) 
2.63”       (0.21”)  
Saint Croix
90.2ºF     (+0.9ºF)
79.4ºF     (+1.4ºF)
84.8ºF     (+1.1ºF)
0.95”       (-1.84”)
 
July 2009 Extremes:
 
 
High:  
Low:  
San Juan
93ºF – July 1st       
75ºF – July 6th & 21st
 
Saint Thomas
92ºF – July 16th & 30th  
75ºF – July 18th & 19th
Saint Croix
92ºF – July 29th & 30th  
76ºF – July 19th & 20th
 
July Historical Statistics:
 
Highest July Temperatures on record:
 
San Juan              
95ºF – July 10th, 1981
94ºF – July 8th, 1995*
*Most recent occurrence  
Saint Thomas      
98ºF – July 27th, 1994
97ºF – July 24th, 1994*
*Most recent occurrence
Saint Croix
94ºF – July 8th & 20th, 1972
93ºF – July 10th, 2007*
*Most recent occurrence
 
Lowest July Temperatures on record:
 
San Juan              
69ºF – July 1st, 1959
70ºF – July 8th, 1961*
*Most recent occurrence
Saint Thomas
66ºF – July 22nd, 1999
68ºF – July 21st, 1999           
70ºF – July 28th, 1994*
*Most recent occurrence
Saint Croix
64ºF – July 5th, 1998
67ºF – July 19th, 1979
68ºF – July 22, 1982*
*Most recent occurrence
 
Wettest Julys:
 
San Juan              
9.35” July 1961
8.92” July 2006
8.51” July 2005
Saint Thomas      
7.41” July 1958
5.74” July 2005
4.85” July 1963
Saint Croix
7.62” July 1958
6.91” July 1964
6.17” July 1960
 
Driest Julys:
 
San Juan              
1.12” July 1974
1.69” July 1971
1.75” July 2008
Saint Thomas
0.03” July 2007
0.24” July 1956
0.74” July 1994
Saint Croix
0.49” July 1976
0.95” July 2009
1.09” July 2002
 

 

2000-2009 Decade in Review:

 
Decadal Observations for San Juan, Puerto Rico:
 
Decadal July High Temperatures:

2000’s
 
1990’s
 
1980’s
 
1970’s
 
1960’s
 
1950’s*
88.8ºF
 
88.6ºF
 
89.6ºF
 
88.5ºF
 
87.3ºF
 
87.3ºF

 
Decadal July Low Temperatures:

2000’s
 
1990’s
 
1980’s
 
1970’s
 
1960’s
 
1950’s*
77.4ºF
 
76.7ºF
 
77.2ºF
 
77.4ºF
 
75.5ºF
 
74.0ºF

 
Decadal July Average Temperatures:

2000’s
 
1990’s
 
1980’s
 
1970’s
 
1960’s
 
1950’s*
83.1ºF
 
82.7ºF
 
83.4ºF
 
83.0ºF
 
81.4ºF
 
80.7ºF

 
Decadal July Precipitation:

2000’s
 
1990’s
 
1980’s
 
1970’s
 
1960’s
 
1950’s*
5.31”
 
5.47”
 
3.84”
 
3.16”
 
6.05”
 
5.22”

* 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 – July precipitation deviations 2000s

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

 

Looking ahead toward the month of August:
 
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”

 
 
Moon/Sun/Tide Data for the month of August:
 
                The sun rises at 6:02 am AST on the 1st of August and sets at 6:59 pm AST, in San Juan, Puerto Rico. This represents a total of 12 hours and 57 minutes of daylight. By August 31st, the sun will rise at 6:10 am AST and set at 6:39 pm AST, providing a total of 12 hours and 29 minutes of daylight, or a total decrease of 28 minutes over the course of the month. At Charlotte Amalie on Saint Thomas, the sun will rise at 5:58 am AST and set at 6:54 pm AST on the 1st of the month. By the end of the month, the sun will rise at 6:05 am AST and set at 6:35 pm AST, representing a total decrease in daylight of 26 minutes for the month.
 
                For the month of August, a full moon will be observed on the 5th of the month at 8:55 pm AST. There will also be a new moon on the 20th of the month at 6:02 am AST. The first quarter of the moon was observed on the 28th of July and the last quarter of the moon will be observed on the 13th of August.
 
                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.
 

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