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

 

August 2010 Highlights:

Temperatures across Puerto Rico ranged from 55ºF in Adjuntas on the 3rd of August to 97ºF in Gurabo on August 29th. Temperatures across the U.S. Virgin Islands ranged from 69ºF, August 28th at Beth Upper New Works on Saint Croix, to 94ºF, recorded at the Cyril E. King Airport on Saint Thomas August 24th. Other notable temperatures for August 2010 are listed below:

 

 
Other Notable August 2010 High’s:
 
Other Notable August 2010 Low’s:
   
 96ºF in Aguadilla on August 29th  60ºF in Ponce on August 31st 
 96ºF in Rio Piedras on August 23rd  62ºF in Toro Negro on August 21st 
 96ºF in Ponce on August 28th     63ºF in Maricao on August 2nd   
 95ºF in Juncos on August 29th  65ºF in Aibonito on August 21st 
 95ºF in Guayama on August 30th  67ºF in Trujillo Alto on August 15th
 94ºF in San Juan, Trujillo Alto, Lajas,  68ºF in Rio Piedras, Lajas, Arecibo

         Palmarejo and Corozal

         and Corozal

*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 August was 4.26”, which fell in Toro Negro over the 24 hour period ending at 8am August 31st. The highest weekly rainfall across Puerto Rico occurred in Paraiso, where 7.56” of rain accumulated the week ending August 13th. Across the U.S. Virgin Islands, the highest 24-hour precipitation total fell at the Cyril E. King Airport on Saint Thomas, where a record 3.02” fell over the 24 hour period ending at midnight on August 30th. For the week ending September 3rd, 3.28” of rain fell at Beth Upper New Works on Saint Croix, representing the highest weekly rainfall across the U.S. Virgin Islands for the month.

 

 Island wide rainfall from across Puerto Rico from January 2 - September 3, 2010.

Figure 1A – Island wide averaged precipitation (and normals) - by week - for the weeks beginning on January 2nd and ending on September 3rd, 2010

 

 Estimated Rainfall for August 2010 using a combination of radar and rain gage data.

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

 

Monthly Weather Summary: 

               August 2010 began under the synoptic influence of an upper level low (TUTT) centered over Hispaniola. This feature enhanced shower and thunderstorm coverage across the local islands, especially across western sections of Puerto Rico the first few days of the month. On August 3rd, an area of unsettled weather over the Atlantic waters was declared Tropical Storm Colin. This storm did not affect the local area as it moved west northwest and away from the region. Days after, a mid to upper level ridge established across the region, resulting in fair weather conditions across the local islands.
 
               Tropical waves, upper level lows as well as low level troughs affected the forecast area during the second and third weeks of the month. As a result, several rounds of disturbed weather persisted across the area. The last week of the month was very active in terms of tropical cyclones. Hurricane Danielle did not have a direct impact across the local islands but brought enough deep moisture across the local islands allowing for active weather across the northern half of Puerto Rico. On August 29th, a tropical storm warning and a hurricane watch were issued for Puerto Rico and the Virgin Islands due to the proximity of Hurricane Earl. This system tracked approximately 100 miles northeast of San Juan and left rainfall accumulations up to 5.98 inches in municipality of Naguabo.
 
               Statistically, August 2010 was above normal in terms of both temperatures and precipitation.  At the Luis Muñoz Marin International Airport in San Juan, the monthly precipitation total of 8.40” was 3.18” above normal. In terms of temperature, the average temperature was 1.8 degrees above normal in August, marking the 15th consecutive month of above normal temperatures recorded in San Juan. The highest monthly temperature in San Juan reached 93 degrees on August 21st, and the lowest temperature fell to 76 degrees on August 30th.
 

August 2010 Statistics:  

 

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

  San Juan
Saint Thomas
Saint Croix
High:   
87.8ºF
90.8 ºF
89.7ºF
Low:  
77.0ºF   
77.7ºF   
77.9ºF
AvgT: 
82.4ºF
84.3ºF
83.8ºF
Pcpn:   5.22” 3.50” 3.81”

 

 

August 2010 Observations:

 

  San Juan Saint Thomas Saint Croix
High:    89.3ºF    (+1.5ºF) 90.0ºF    (-0.8ºF) 89.3ºF    (-0.4ºF)
Low:   79.1ºF    (+2.1ºF) 80.7ºF    (+3.0ºF) 77.7ºF    (-0.2ºF)
AvgT:  84.2ºF    (+1.8ºF) 85.3ºF    (+1.0ºF) 83.5ºF    (-0.3ºF)
Pcpn:  
8.40”      (+3.82”)
5.49”      (+1.99”)
3.43”      (-0.38”)

August 2010 Extremes:

  San Juan Saint Thomas Saint Croix
High:   94ºF – August 5th 94ºF – August 24th 92ºF – August 24th  
Low:  
76ºF – August 30th   
78ºF – August 30th
73ºF – August 20th & 21st

 

August Historical Statistics:   

 

 

Highest August Temperatures on record:

San Juan    Saint Thomas  Saint Croix
97ºF – August 21st, 1980 99ºF – August 4th, 1994 & 95ºF – August 25th, 1999 &
96ºF – August 20th, 1980 & August 8th, 1979 August 19th, 1972
August 23rd, 1974 98ºF – August 13th, 1994* 94ºF – August 3rd & 4th, 1972
95ºF – August 26th, 2009*
*Most recent occurrence
93ºF – August 8th, 2009*
*Most recent occurrence    
*Most recent occurrence

Lowest August Temperatures on record:

San Juan         Saint Thomas Saint Croix
70ºF – August 24th & 26th, 1956 64ºF – August 1st & 2nd, 1972 63ºF – August 17th, 1978
71ºF – August 23rd, 2000* 67ºF – August 12th, 1956 67ºF – August 31st, 1979 &
*Most recent occurrence
70ºF – August 18th, 1982* August 16th, 1978
 
*Most recent occurrence
68ºF – August 2nd, 1983*
   
*Most recent occurrence

Wettest Augusts:

San Juan   Saint Thomas      Saint Croix
11.31” August 1988 8.54” August 1963 11.41”  August 1979
9.52” August 2000 8.22” August 2005 11.04”  August 1989
9.38” August 1979
6.71” August 1955
 

Driest Augusts:

San Juan    Saint Thomas Saint Croix
1.83” August 1984 0.70” August 1993 1.35” August 2005
1.93” August 1982 0.98” August 1991 1.40” August 1980
1.94” August 1991
1.26” August 2002
1.51” August 2009
 

 

2000-2010 Decade in Review:

 

 

          August 2010 marked the 15th consecutive month of above normal temperatures in San Juan. Thanks to a recent study on El Niño and the Southern Oscillation, it was noted that this string on abnormally warm temperatures was likely influenced by a strong El Niño which persisted across the tropical Pacific through April 2010. Additionally, with a La Niña advisory now in effect, it is thought that this string of abnormally warm temperatures could come to an end in the upcoming months.

          Thanks to record rainfall associated with Hurricane Earl as it passed to the northeast of the local islands from August 30th – 31st, August 2010 was another abnormally wet month across the local islands. By the end of the month, 157% and 161% of the normal monthly precipitation accumulated at Charlotte Amalie on Saint Thomas and in San Juan respectively. Additionally, as of September 1st, 2010, this year continues to be on track to be the wettest year on record in San Juan, with the latest cooperative weather data indicating the island had received 138% of its normal precipitation through the 1st of the month.

          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. Additionally, a summary of the August 2010 data for San Juan along with the previous 6 decades of data from San Juan has also been included below.

 

 

 

Decadal Observations for San Juan, Puerto Rico:      

 

  

Decadal August High Temperatures:

2010
2000’s
1990’s
1980’s
1970’s
1960’s
1950’s
89.3ºF
89.0ºF
89.4ºF
89.9ºF
88.3ºF
87.8ºF
88.1ºF

Decadal August Low Temperatures:

2010
2000’s
1990’s
1980’s
1970’s
1960’s
1950’s
79.1ºF
77.6ºF
77.3ºF
77.0ºF
77.3ºF
75.6ºF
74.1ºF

Decadal August Average Temperatures:

2010
2000’s
1990’s
1980’s
1970’s
1960’s
1950’s
84.2ºF
83.3ºF
83.3ºF
83.4ºF
82.8ºF
81.6ºF
81.1ºF

Decadal August Precipitation:

2010
2000’s
1990’s
1980’s
1970’s
1960’s
1950’s
8.40”
5.92”
4.83”
5.08”
5.27”
6.13”
6.45”

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

  

Temperatures since 2000 for the month of August in San Juan, PR.

Figure 2 - Temperature deviations for San Juan, PR

 Temperatures since 2000 for the month of August on Saint Thomas, USVI.

Figure 3 - Temperature deviations for Saint Thomas, VI

 Temperatures since the year 2000 for the month of August on Saint Croix, USVI

Figure 4 - Temperature deviations for Saint Croix, VI

 August precipitation since the year 2000 for San Juan, PR, Saint Thomas, USVI and Saint Croix, USVI.

Figure 5 - August 2000's precipitation deviations from normal

 2010 Year to Date Precipitation Deviations from normal for San Juan, PR, Saint Thomas, USVI and Saint Croix, USVI.

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

 

Looking ahead toward the month of September: 

 

          Looking ahead, September marks the peak of hurricane season across Puerto Rico and the U.S. Virgin Islands. Additionally, September is the 2nd wettest month on average in San Juan, with the Luis Muñoz International Airport receiving 5.60” of rainfall. (A record 15.15” of rain fell in September 1996 and the driest September on record was September 1987, when only 1.73” of rainfall was recorded in San Juan). The mean temperature at the Luis Muñoz International Airport in San Juan for September is 82.2ºF, which is tied with July for the 2nd warmest month of the year (August  is the warmest month on average, with a average temperature of 82.4ºF. The August 2010 outlook for the remainder of the 2010 Atlantic hurricane season indicates a 100% chance of a normal or above normal hurricane season. This outlook is based on strengthening La Niña conditions and multi-decadal conditions. The latest official discussion from the climate prediction center regarding the current hurricane season outlook can be viewed at: http://www.cpc.noaa.gov/products/outlooks/hurricane.shtml 

 

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

 

   San Juan  Saint Thomas Saint Croix
High:      87.8ºF 90.2ºF    89.2ºF
Low:   76.5ºF  76.9ºF   76.8ºF
AvgT:    82.2ºF 83.6ºF 83.0ºF
Pcpn:  
5.60”
5.34”
5.36”

 

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

 

 

          The sun rises at 6:10 am AST and sets at 6:39 pm AST, in San Juan, Puerto Rico on September 1st. This represents a total of 12 hours and 29 minutes of daylight. By September 30th, 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 in 30 minutes over the course of the month. The transition from summer to fall begins on September 23rd, which marks the first full day of autumn.

          At Charlotte Amalie on Saint Thomas, the sun will rise at 6:05 am AST and set at 6:34 pm AST on the 1st 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, representing a total decrease in daylight of 30 minutes over the course of the month.

 
          For the month of September, a full moon will be observed on the 23rd of the month. There will also be a new moon on the 8th of the month. The last quarter of the moon was observed on the 1st and the first quarter of the new moon will be observed on the 15th 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.

 

 

Click here to return to the local data/records section of the NWS San Juan climate page

 

 


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