Climate Notes March/April 2008:

March generally is the last month of the dry season here in Puerto Rico. On average, the Luis Muñoz International Airport receives only 2.17 inches of rain during the month of March* (far shy of the 6.03 inches of rainfall normally received during November), making March the driest month on the island. March also is one of the cooler months on the island, with an average daily temperature of 78.0 ºF*, 1.2 ºF warmer than January, the coolest month of the year, yet 4.7 ºF cooler than August, the warmest month.

Islandwide, Puerto Rico received, on average, approximately 1.13" less rainfall than normal, or 52% of the normal value, for the month of March. Above normal precipitation was reported along the northern and southern coasts during the first three weeks of the month, however the remainder of the island was significantly drier than normal, heavily weighting the final statistic for the month. By the end of March, Puerto Rico's rainfall had fallen to 82% of the average year-to-date, prompting the Climate Prediction Center (CPC) to classify much of the island as abnormally dry on April 8, 2008. The highest maximum temperature recorded for the month was 90 degrees F, reported both in Ponce multiple times and in Lajas on March 1, while the coldest temperature recorded for the month was 48 degrees F, reported in Adjuntas on both the 9th and 27th of March .

At the Luis Muñoz International Airport in San Juan, the average monthly temperature was 77.8 ºF*, which was -0.2 ºF lower than average, with a maximum temperature of 87 ºF, reported on the 28th of the month, and a minimum temperature of 70 ºF, reported several times. This marked the 3rd straight month that below average temperatures were recorded in San Juan. A total of 0.58 inches of rainfall was reported at the Luis Muñoz International Airport, which was 1.59” inches below normal, well shy of the record 5.41” recorded in March, 1958. The driest March on record was March 2005, the only month on record when no measureable rainfall was recorded in San Juan.

Looking ahead, April generally marks the transition to the wet season here in Puerto Rico, with the Luis Muñoz International Airport in San Juan receiving 4.17” of rainfall on average*, with a record of 15.00” received in April 2005. However, not all April’s are wet, with the second driest month on record occurring in April 1997, when only 0.08” of rainfall was recorded in San Juan. The average high temperature at the Luis Muñoz International Airport in San Juan for April is 79.4 ºF*, 1.4 ºF warmer than March. Presently, La Niña conditions are expected to continue for at least 3 more months, and a detailed summary of these current ENSO conditions and forecasts can be found at:

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.pdf

* All climate averages for San Juan taken from 52 continuous year period of 1956-2007 *