May 2010 Climate Report for Puerto Rico and the U.S. Virgin Islands

 

May 2010 Highlights:
   
Temperatures across Puerto Rico ranged from 54ºF in Adjuntas on the 7th of May to 97ºF in Gurabo on May 1st. Temperatures across the U.S. Virgin Islands ranged from 72ºF, May 6th at Christiansted Airport on Saint Croix, to 90ºF, recorded at both the Cyril E. King Airport on Saint Thomas and Fort Christiansted on Saint Croix. Other notable temperatures for May 2010 are listed below:
 

Other Notable May 2010 High’s:
 
94ºF in Lajas on May 26th
94ºF in Ponce on May 17th
93ºF in Juncos on May 1st   
93ºF in Aguadilla on May 17th
92ºF at Trujillo Alto, Guayama, Dos Bocas and Corozal on various days of the month.
 
Other Notable May 2010 Low’s:
 
58ºF in Coloso on May 6th 
61ºF in Toro Negro on May 4th    
62ºF in Maricao on May 7th    
63ºF in Aibonito on May 5th   
63ºF in Ponce on May 6th
 

*If multiple occurrences, all dates above reflect the latest occurrence of the month.
 
The highest 24-hour precipitation total across Puerto Rico for the month of May was 8.00”, which fell at Toro Negro over the 24 hour period ending at 8am May 29th. The highest weekly rainfall across Puerto Rico occurred at the Maricao Fish Hatchery, where 9.50” of rain accumulated the week ending May 14th. Across the U.S. Virgin Islands, the highest 24-hour precipitation total was at Coral Bay on Saint John, where 2.72” fell over the 24 hour period ending at 8am on May 8th. For the week ending May 14th, 4.40” of rain fell at Coral Bay on Saint John, representing the highest weekly rainfall across the U.S. Virgin Islands for the month of May.
 

 Island wide averaged rainfall through May 28, 2010 for Puerto Rico

Figure 1A – Island wide averaged precipitation (and normals) - by week - for the weeks beginning on January 2nd and ending on May 28, 2010

 

 San Juan Estimated rainfall from AHIPS for the month of May 2010

Figure 1B – Graphical Display of May 2010 precipitation across Puerto Rico and the U.S. Virgin Islands derived from a combination of rain gage and radar data.

 

Monthly Weather Summary: 

 

May 2010 began with an area of surface high pressure extending across the eastern Caribbean. This area of surface high pressure slowly shifted eastward into the central Atlantic during the first week of the month, resulting in locally breezy winds across Puerto Rico and the U.S. Virgin Islands. Days after, a series of troughs brought additional moisture and instability across the local region, producing shower and thunderstorm activity, mainly activity across the northern and western sections of Puerto Rico. Towards the middle of the month, deep moisture from the tropics spread northward and prevailed across the local islands for the last two weeks of May. This deep moisture, combined with favorable atmospheric conditions, local effects and a low level trough to the north of Puerto Rico, brought widespread flooding rains across Puerto Rico and the U.S. Virgin Islands the last few days of the month.

Not surprisingly, May 2010 was well above normal in terms of precipitation, with the San Juan area averaging 7.23 inches of rainfall above normal. This surplus in rainfall made May 2010 the 4th wettest May on record. In fact, May 2010 was also the 9th wettest month on record since 1956, with the total accumulated precipitation of 31.21" through the end of May representing the wettest start to a year on record. In addition May 2010 finished 1.5 degrees warmer than average, making it the 12th consecutive month at the Luis Muñoz Marin International Airport in San Juan where the average temperature was above normal.

 

May 2010 Statistics:

 
 
Average May Temperatures/Precipitation (NCDC 1971-2000 averages):
 
 
High:     
Low:     
AvgT:   
Pcpn:      
San Juan              
86.3ºF
74.9ºF    
80.6ºF
5.29”
Saint Thomas
87.9ºF    
75.9ºF    
81.9ºF
3.36”
Saint Croix
87.5ºF
75.9ºF
81.7ºF
3.62”
 
May 2010 Observations:
 
 
High:     
Low:     
AvgT:   
Pcpn:      
San Juan
87.3ºF     (+1.0ºF)
76.9ºF     (+2.0ºF) 
82.1ºF     (+1.5ºF) 
12.52”     (+7.23”)
Saint Thomas
87.2ºF     (-0.7ºF)  
78.4ºF     (+2.5ºF) 
82.8ºF     (+0.9ºF) 
5.21”       (+1.85”)
Saint Croix
87.5ºF     (+0.0ºF)
76.9ºF     (+1.0ºF)
82.2ºF     (+0.5ºF)
6.00”       (+2.38”)
 
May 2010 Extremes:
 
 
High:  
Low:  
San Juan
91ºF – May25th & 26th
73ºF – May 2nd    
Saint Thomas
90ºF – May14th     
75ºF – May 2nd & 5th
Saint Croix
89ºF – May 13th & 14th  
72ºF – May 6th  
 
 

May Historical Statistics: 

 
Highest May Temperatures on record:
 
San Juan              
96ºF – May 5th & 11th, 1980
95ºF – May 21st, 2005*
*Most recent occurrence  
Saint Thomas      
97ºF – May 23rd, 1996*
*Most recent occurrence
Saint Croix
94ºF – May 28th, 1972
93ºF – May 25th, 1994*
*Most recent occurrence
 
Lowest May Temperatures on record:
 
San Juan              
66ºF – May 5th, 1962
67ºF – May 6th, 1962 & May 18th, 1957
68ºF – May 2nd, 1963*
*Most recent occurrence
Saint Thomas
66ºF – May 5th, 1974
68ºF – May11th, 1986*
*Most recent occurrence
Saint Croix
63ºF – May 4th, 1992
64ºF – May 15th, 1975 & May 15th, 1972
65ºF – May 8th, 1982*
*Most recent occurrence
 
Wettest Mays:
 
San Juan              
14.99” May 1965
13.59” May 1958
12.80” May 1986
Saint Thomas      
16.39” May 1960
9.98” May 1979
9.80” May 198
Saint Croix
14.03”  May 1981
11.38”  May 2001
8.89”  May 1987
 
Driest Mays:
 
San Juan              
0.44” May 1972
0.48” May 1973
1.04” May 1975
Saint Thomas
0.06” May 2008
0.28” May 2007
0.47” May 1973
Saint Croix
0.22” May 1974
0.28” May 2005
0.37” May 2003
  
 

 

 

2000-2010 Decade in Review:

 

 

                May 2010 marked the 12th consecutive month of above normal temperatures in San Juan. May 2010 was also the 4th wettest May on record in San Juan and ranked among the top 10 wettest at both the Cyril E. King Airport on Saint Thomas and the Christiansted Airport on Saint Croix. In fact, 2010 has generally been a very wet year to date across Puerto Rico, so far ranking as the wettest start to a year since record keeping began in San Juan. For a look at temperature and precipitation deviations for San Juan, Saint Thomas and Saint Croix from their NCDC averages, see Figures 2 to 6 below. 

 

 

Decadal Observations for San Juan, Puerto Rico:

 

 

 
Decadal May High Temperatures:
2010
2000’s
1990’s
1980’s
1970’s
1960’s
1950’s
87.3ºF
87.4ºF
87.8ºF
88.2ºF
87.4ºF
86.0ºF
85.4ºF
 
 
Decadal May Low Temperatures:
2010
2000’s
1990’s
1980’s
1970’s
1960’s
1950’s
76.9ºF
75.6ºF
75.4ºF
75.0ºF
75.0ºF
73.2ºF
71.9ºF
 
Decadal May Average Temperatures:
2010
2000’s
1990’s
1980’s
1970’s
1960’s
1950’s
82.1ºF
81.5ºF
81.6ºF
81.6ºF
81.2ºF
79.6ºF
78.6ºF
 
 
Decadal May Precipitation:
2010
2000’s
1990’s
1980’s
1970’s
1960’s
1950’s
12.52”
5.02”
4.35”
7.59”
4.25”
6.41”
8.13”
 
* Records for San Juan began on January 1st, 1956
      
 

  

Temperature deviations for the month of May since 2000 for San Juan

Figure 2 - Temperature deviations for San Juan, PR

 Temperature deviations for the month of May since 2000 on Saint Thomas

Figure 3 - Temperature deviations for Saint Thomas, VI

 Temperature deviation for the month of May since 2000 for Saint Croix

Figure 4 - Temperature deviations for Saint Croix, VI

 Precipitation Deviations for the month of May since 2000 for Puerto Rico and the USVI

Figure 5 - May 2000's precipitation deviations from normal

 Year to date plot of percent of normal precipitation received across Puerto Rico and the USVI

 Figure 6 - January - May 2010 precipitation deviations for San Juan, Saint Thomas, and Saint Croix 

 

Looking ahead toward the month of June:

 

Looking ahead, June is the 5th driest month across Puerto Rico, with the Luis Muñoz International Airport in San Juan receiving 3.52” of rainfall on average. A record 10.96” of rain fell in June 1965 and the driest June on record was June 1985, when only 0.29” of rainfall was recorded in San Juan. The average temperature at the Luis Muñoz International Airport in San Juan for June is 82.1ºF, making June the 4th warmest month of the year. Presently, we are experiencing ENSO-neutral conditions with a La Niña Watch now in effect.

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.pdf 
 
This transition has an impact on expectations for the hurricane season, with NOAA currently forecasting a 95% of a near or above normally active hurricane season.

 

 

 

 

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

 
High:     
Low:     
AvgT:   
Pcpn:      
San Juan              
87.6ºF
76.6ºF    
82.1ºF
3.52”
Saint Thomas
89.5ºF    
77.4ºF    
83.5ºF
2.35”
Saint Croix
88.6ºF
78.1ºF
83.4ºF
2.30”

 

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

 

 

             The sun rises at 5:47 am AST and sets at 6:57 pm AST, in San Juan, Puerto Rico on June 1st. This represents a total of 13 hours and 10 minutes of daylight. By June 30th, the sun will rise at 5:51 am AST and set at 7:05 pm AST, providing a total of 13 hours and 14 minutes of daylight, or a total increase in 4 minutes over the course of the month. The summer solstice, or the longest day of the year in the Northern Hemisphere, will be celebrated on June 21st, with a total of 13 hours and 15 minutes of daylight in San Juan.
 
At Charlotte Amalie on Saint Thomas, the sun will rise at 5:43 am AST and set at 6:52 pm AST on the 1st of the month. By the end of the month, the sun will rise at 5:47 am AST and set at 7:00 pm AST, representing a total increase in daylight of 4 minutes over the course of the month.
 
            For the month of June, a full moon will be observed on the 26th of the month at 7:30 am AST. There will also be a new moon on the 12th of the month at 7:15 am AST. The last quarter of the moon will be observed on the 4th of June and the first quarter of the new moon will be observed on the 19th of the month.
 
            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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