Severe Thunderstorm Outbreak Possible in the Upper Midwest on Monday

Multiple corridors of severe thunderstorms are expected across the Upper Midwest on Monday into Monday night, with a regional severe weather outbreak possible. The most dangerous period is likely during the late afternoon and evening when strong tornado potential should be maximized. Scattered large to very large hail and damaging winds are likely as well. Read More >

2010 Climate Statistics for San Juan, PR

2010 Highlights:

2010 was the Wettest Year on Record across the San Juan Area (since 1898)
2010 was the Second Wettest Year on Record at Charlotte Amalie, Saint Thomas (Since 1953)
2010 was the Seventh Wettest Year on Record at Christiansted Airport, Saint Croix (Since 1951)
2010 was the Sixth Straight Year with above normal temperatures in San Juan (Temperatures were 0.4°F below normal on Saint Croix and 0.5°F below normal on Saint Thomas)
2010 was the Tenth Straight Year with an average temperature above 80°F in San Juan (average is 80.2°F)
December 2010 was the coolest December on record at the Cyril E. King Airport on Saint Thomas and the coolest month there since January 1955
December 2010 was the 2nd coolest December on record at the Christiansted Airport on Saint Croix and the coolest month there since April 1982
December 2010 was the first month with below normal temperatures in San Juan since March 2009 (This broke a string of 20 straight months with above normal temperatures in San Juan)
December 2010 was the driest December on record at the Chirstiansted Airport on Saint Croix

Annual Weather Summary:

2010 began with a period of unusually warm weather across the local islands. On January 2nd, 2010, the temperature soared to 89°F at the Luis Muñoz Marin International Airport in San Juan, which surpassed the previous record of 87°F for the date (set back in 1996). Two days later, on January 4th, 2010, a new record high temperature for the date was also set when the temperature reached 88°F. However this warm weather did not last, and by the middle of the month, unseasonably cool temperatures were observed. On January 15th, 2010, the high temperature of 77°F at the Luis Muñoz Marin International Airport in San Juan represented the coolest high temperature ever recorded for that date (the previous record was 78°F, which was recorded back in 1962). However, even with this cool period of weather over the middle portion of the month, January 2010 ended 1.4 degrees above normal in San Juan, while temperatures across the USVI ended very near normal. In terms of precipitation, January 2010 ended as the wettest January ever recorded at the Luis Muñoz Marin International Airport in San Juan. By the end of the month, a total of 11.07 inches of rainfall accumulated at the airport, which was approximately 4 inches shy of the all time record of 15.47 inches for the San Juan Area, which was recorded in 1937.

Throughout the month of February, unusually warm and dry weather prevailed across the local islands. By the end of the month, February 2010 ranked as the warmest February since 1898 and the 11th driest February across the San Juan Area. The average temperature for the month was 80.0 degrees; which was 3.1 degrees above normal.

During the first week of March, a cold front stalled across Puerto Rico and the U.S. Virgin Islands from the evening of March 5th through early March 8th. New daily record precipitation totals for both the airports in San Juan and on Saint Thomas were recorded with this event. In addition, during the same time frame, the high temperature of 74°F recorded March 7th, 2010, represented the second coolest high temperature ever recorded at the Luis Muñoz Marin International Airport in San Juan.

April 2010 was above normal in terms of temperature, and slightly below normal, in terms of precipitation, across the local islands. The average temperature in San Juan was 1.7 degrees above normal, and the monthly rainfall was 0.25 inches below normal at the airport. Towards the end of the month, the mercury reached 93°F and 94°F in San Juan on April 27th and 28th, tying the previous records for those dates (recorded in 1992 and 1978 respectively). Additionally, the low temperature at the Luis Muñoz Marin International Airport in San Juan fell to only 80°F early on the morning of April 23rd, 2010, which surpassed the previous record warm minimum temperature for the date of 78°F set back in 1987. In addition, April 23rd now marks the earliest date on record that the temperature has not fallen below 80°F in San Juan.

May 2010 was well above normal in terms of precipitation across much of the region, with the Luis Muñoz Marin International Airport receiving 7.23 inches more rainfall than 30-year normal. This surplus in rainfall made May 2010 the 4th wettest May on record at the Luis Muñoz Marin International Airport in San Juan.

By June, the first strong tropical wave of the season brought very heavy rainfall and cool temperatures to the region. Widespread rainfall totals of 4 to 6 inches were observed across eastern and southeastern sections of Puerto Rico during this event, while the heaviest rainfall accumulated across the US Virgin Islands, Culebra and Vieques. In addition, both the Cyril E. King airport on Saint Thomas and the Christiansted airport on Saint Croix recorded their wettest 3-day period ever for the month of June with this event. Moreover, the high temperatures of 82°F and 83°F on Saint Thomas for the 20th and 19th of the month respectively, were the coolest high temperatures ever recorded on those dates.

Days after, during the late afternoon of Thursday, July 1st, 2010, several reports of very strong winds in the vicinity of the Mayaguez Airport were received. An observer on duty at the airport reported that he had measured winds of approximately 40 knots (44 mph), with a sudden gust of 72 knots (80 mph), during this event. These strong winds were observed without the presence of a funnel cloud, tornado, or hail. Given the data available, and the reports from the field, this wind event could be classified as a wet mini-microburst.

August 30th-31st, the passage of Hurricane Earl to the northeast of the local islands broke several additional rainfall records across Puerto Rico and the U.S. Virgin Islands. For the 24-hour period ending at midnight on August 30th, new rainfall records were established at the airport in San Juan (3.52 inches), at the Christiansted Airport on Saint Croix (1.91 inches) and at the Cyril E. King Airport on Saint Thomas (3.02 inches).

This wetter pattern continued through October. Very impressive rainfall amounts accumulated across the islands during the five day period, which began on October 4th and ended on October 8th. This rainfall was associated with the passage of a tropical wave that eventually became Subtropical Depression Seventeen on the morning of Wednesday October 6th. This system then transitioned into Hurricane Otto on the afternoon of October 8th. Although the U.S. Virgin Islands and Puerto Rico remained well to the southeast and south of the tropical storm wind field, the distant rain bands which formed Otto’s tail impacted the local area for many days, pulling moist and unstable tropical air northward across the islands. Thanks to the record rainfall that accumulated with the tail of moisture feeding into Hurricane Otto, October 2010 was the wettest October on record at the Cyril E. King Airport on Saint Thomas. In addition, the 16.20 inches of rainfall that accumulated over the month represented the 3rd wettest month on record at the airport since 1953.

By the end of 2010, a cool and drier air mass combined with clear skies and light winds, resulted in new record low temperatures across the U.S. Virgin Islands over the weekend of December 3rd, 2010. New record low temperatures were established at the Christiansted Airport on Saint Croix for the mornings of December 2nd – 5th, 2010. At the Cyril E. King Airport on Saint Thomas, new record low temperatures were established on both December 3rd and December 5th, 2010. Days after, a cold front brought persistent periods of light to moderate rainfall across much of northern Puerto Rico beginning the evening of December 14th, 2010 and continuing throughout the day of December 15th, 2010. Due to this persistent rainfall and thick cloud cover, the temperature peaked at only 76°F in San Juan on Wednesday, December 15th, 2010. This marked the coolest day in the San Juan Metro Area for December 15th since 1898, and the coolest day in San Juan since March 7th, 2010, when the temperature reached only 74°F at the airport. As a result of the impressive rainfall that accumulated over the course of the year, 2010 ended as the wettest year on record across the entire San Juan Metro Area and second wettest year at the Cyril E. King Airport on Saint Thomas. In the end, a total of 89.51 inches of rainfall accumulated at the Luis Muñoz Marin International Airport in San Juan; approximately 2 inches more than the previous record for the metro area of 87.55 inches, that was recorded in 1931.

Summary of 2010 Statistics including the USVI:

2010	Maximum Temperature	Minimum Temperature	Precipitation

*San Juan, PR* *(Departure from Normal)*	86.6°F (+1.1°F)	75.8°F (+1.6°F)	89.51 inches (+38.75 inches)

*Saint Thomas, USVI* *(Departure from Normal)*	85.9°F (-2.3°F)	76.9°F (+1.9°F)	61.38 inches (+23.51 inches)

*Saint Croix, USVI* *(Departure from Normal)*	86.3°F (-0.8°F)	74.9°F (-0.1°F)	50.64 inches (+10.80 inches)