Collage of Pictures from around Puerto Rico.

Tracking the 2010 Record Rainfall in the San Juan, PR Area

 

          While only a Trace of rainfall accumulated on the final day of 2010 at the Luis Muñoz Marin International Airport in San Juan, a record 89.51 inches of rain fell over the course of the year. This total first surpassed the annual rainfall record at the Luis Muñoz Marin International Airport back on the 7th of November (the previous record was 77.28 inches recorded back in 2005) and surpassed the annual record for the San Juan Area on the 20th of December (click here to see a loop of the radar imagery associated with the frontal boundary that broke the annual rainfall record for the San Juan Area December 20th-21st, 2010). While records for the airport date back to January 1st, 1956, National Weather Service statistics for the San Juan Metro Area date back to 1898. Prior to 1956, the official San Juan weather observation station moved between multiple locations in Old San Juan and the Isla Grande Airport (click here for a complete history of the NWS in San Juan).

 

Top 10 Wettest Years in the San Juan, PR Area 

Rank

Precipitation Amount  (inches)

Year

1

89.51 inches

2010

2

87.55 inches

1931

3

84.97 inches

1950

4

84.93 inches

1927

5

78.96 inches

1902

6

77.61 inches

1899

7

77.28 inches

2005

8

76.60 inches

1952

9

75.70 inches

1901

10

74.55 inches

1979

 

          Thanks in part to a favorable ENSO cycle this past year, with a strong El Niño persisting through the dry season and the rapid development of La Niña conditions as we transitioned into the wet season, this wet weather across the Northeastern Caribbean was not limited to San Juan. According to Cooperative Weather Observer data, 2010 was also wet across the entire forecast area, with 132% of the normal precipitation falling across all of Puerto Rico and 170% of the normal precipitation falling across the U.S. Virgin Islands (through December 31st). In addition, 2010 ranked as the second wettest year on record at Charlotte Amalie on Saint Thomas and the 7th wettest year at the Christiansted Airport on Saint Croix. See the table below for plots of how 2010 stacked up against some of the previous wettest years on record in San Juan and at Charlotte Amalie.

 

Accumulative Precipitation in San Juan for the 3 of the wettest years on record.
Accumulative Precipitation for 3 of the wettest years on record in Charlotte Amalie.

*Records for the San Juan Area date back to 1898 and to 1953 for Saint Thomas

 

          While rainy days were frequent across the local islands this past year, 2010 did not end with the most rainy days on record in the San Juan Area. Over the course of the year, there were 199 days with measurable rainfall recorded in San Juan, far shy of the 242 days that occurred in 1950 and very near the average of approximately 202 days. A summary of the historical frequency of days with varying amounts of precipitation across the San Juan Area along with the corresponding average number of days observed over the past 112 years can be found below.

 

Frequency of Precipitation Amounts in the San Juan, PR Area

Precip. Value

Days in 2010

Max Days

Year

Min Days

Year

Average Days

0.01" +

199

242

1950

170

1983

202.2

0.25" +

95

95

2010

34

1983

62.3

1.00" +

28

28

2010

3

1971

12.4

2.00" +

6

10

1927

0

1921

2.9

 

 Click here to return to unique local climate data web page for the NWS San Juan

 


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