March 5, 2021

Drought Update for Puerto Rico and the U.S. Virgin Islands

Drought conditions continue to prevail across northwest Puerto Rico and the US Virgin Islands. Expansion of abnormally dry/moderate drought and some additional deterioration is likely into late April, before the usual onset of the wet season.
Key Points

  • Puerto Rico Conditions: Light passing showers continued across the island, preventing any further deterioration across eastern sections, but it was not enough to improve burgeoning dryness and drought conditions in the northwest and southern slopes of Puerto Rico.
  • U.S. Virgin Islands Conditions: Drought conditions continue to prevail across Saint Thomas, Saint John, and Saint Croix.
  • Puerto Rico Impacts: An increased number of grass fires have been observed across northwest Puerto Rico, particularly in the vicinity of Anasco, Rincon, Moca, and San Sebastian. 
  • U.S. Virgin Islands Impacts: Drought is a growing concern for many farmers. Soil and vegetation in the USVI is visibly showing signs of distress such as soil cracking and decreased soil moisture.
  • Looking Ahead: The long term forecast suggests drought conditions are likely to expand and/or worsen during the next few months.
  • For weather information specific to your area, please monitor products issued by the National Weather Service in San Juan, Puerto Rico.

Current Conditions
Drought Conditions

  • Puerto Rico: Abnormally dry conditions are observed across northwest and south of the main island, as well as the islands of Vieques and Culebra. Nearly 23% of Puerto Rico is classified by the US Drought Monitor as being abnormally dry, while 18% of the island, all in the northwest, is classified as moderate drought (Figure 1).
  • U.S. Virgin Islands: Moderate drought conditions are now observed on all the islands (Figure 2).
Figure 1. Latest drought assessment for Puerto Rico issued by the US Drought Monitor.
Figure 2. Latest drought assessment for the US Virgin Islands issued by the US Drought Monitor.

Rainfall Deficits

  • Puerto Rico: 90-day rainfall deficits across northwest Puerto Rico range from 4 to 8 inches. Conditions elsewhere vary between slightly above to slightly below normal (Figure 3).
  • U.S. Virgin Islands: The 90-day rainfall deficits across the U.S. Virgin Islands range from 2 to 4 inches.
Figure 3. 90-day rainfall deficits across Puerto Rico.

Soil Moisture Conditions in Puerto Rico

  • The driest soils and highest crop stress in Puerto Rico is currently observed in the northwest, as well as in the southern slopes. This is based on soil moisture data from the Puerto Rico Agricultural Water Management / PRAGWATER (Figure 4 and 5).
Figure 4. Latest assessment of soil saturation for Puerto Rico. Soil saturation: 1=Saturated.
Figure 5. Latest assessment of crop stress factor for Puerto Rico. Crop Stress Coefficient: 1=No Stress, 0=Extreme Stress.

Reservoirs and Streamflow Conditions in Puerto Rico

  • The 28-day average streamflow from the U.S. Geological Survey (USGS) river gauge network indicated most of the streamflows running at normal levels across the eastern sections of the island of Puerto Rico. However, there are several streams running below normal levels across central and west sections of the island (Figure 6).
Figure 6. Current 28-day average streamflow retrieved from the US Geological Survey.

Groundwater Conditions

  • The groundwater level retrieved from the U.S. Geological Survey (USGS) network indicated most of the wells across Puerto Rico and the U.S. Virgin Islands are at normal levels except for a few outliers across north and south Puerto Rico (Figure 7). 
Figure 7. Current groundwater level retrieved from the US Geological Survey. 
Outlooks and Impacts
Rainfall Outlook

  • Based on the 3-month extended forecast by the Caribbean Climate Outlook Forum (CariCOF), there is a higher chance to observe below normal rainfall across the local islands through May. Therefore, drought conditions are likely to expand and/or worsen during the next few months.
Figure 8. Latest extended forecast issued by the Caribbean Climate Outlook Forum.
Sector Impacts

General conditions

  • St. John, USVI. Normally, December winds and rain allow for cooler temperatures. However, this year those winds appeared later in January and February. The winds are contributing to decreased soil moisture, and vegetation is showing signs of distress earlier than in previous years.
  • St. Thomas, USVI. Moderate drought conditions are beginning to show on vegetation across the island. 
  • St. Croix, USVI. Conditions on St. Croix have been relatively mild with some scattered rain showers even as we head into our traditional dry season. Ponds are maintaining water at usable levels so far.

Forest and fire conditions

  • Region-wide. Seasonal drying conditions have been increasing fire risk toward the end of February, particularly in western Puerto Rico (NWS Fire weather zone PRZ018), southeast and southwest coastal plains Puerto Rico zones (PRZ027, PRZ014), and Saint Croix (VIZ002). Red flag warnings were issued for the southern coastal plain in late February indicating critical fire weather conditions have been occurring due to a combination of strong winds, low relative humidity, and warm temperatures. Brush fires are occurring in western Puerto Rico. Fire danger risk is likely to persist until the region receives significant rainfall.

Specialty and row crops

  • St. Thomas, USVI. Farmers are beginning to see the impacts of a moderate drought on vegetation island-wide. Row and specialty crops farmers are not yet buying water. However, they are beginning to use drip irrigation during the daytime as the ground dries quickly. They are also starting to put in place conservation plans so they will have enough water throughout the dry season leading up to summer when temperatures rise. 
  • St. John, USVI. Farmers are sharing that all indications show a very dry January and February. Many farmers are using drip irrigation, and they are working to rotate specialty and row crops so that they can conserve water. They indicate that they are watering earlier in the day and later in the afternoon to limit water loss due to evaporation. Finally, Coral Bay farmers noted that cracks are already appearing in the soil due to a lack of moisture.  
  • St. Croix, USVI. Drought is a growing concern for many farmers. Those without well access reported that they are using home water systems including cisterns when additional water is necessary. The Virgin Islands Department of Agriculture (VIDOA) indicated that water is being provided to farmers; more than 728,900 gallons provided in February, 704,000 gallons in January, and 492,580 gallons in December). The UVI Agricultural Experiment Station (AES) indicated that many farmers are also using irrigation to conserve water and noted that vegetation is beginning to show signs of browning, and becoming drier as the season warms up. 

Fruit trees

  • Puerto Rico. The effects of drought are being observed in the foliage of fruit trees in the southwest and northwest area of Puerto Rico. The drought has affected the size and quality of the fruit. The leaves are curled and have a yellowish color, while the fruits are small. If the drought continues, many fruit trees will begin to lose their foliage and fruit production. 

Diary, livestock and pasture

  • Puerto Rico. Rain has been scarce in Southwestern Puerto Rico for the last 2 months. Some ranches are now maintaining cattle in semi-confinement and supplying hay, with sheep grazing during the afternoon hours. 
  • St. Croix, USVI. Pastures are showing some early signs of forage being impacted by the decreasing rainfall such as slower regrowth after grazing and some signs of browning. Farmers are rotating livestock in different areas to ensure they have enough native forage to eat. AES staff noted that livestock farmers are also working to capture water for use in the dry season. Some farmers have already resorted to off-site forage harvesting (cut and carry) to supplement their pastures. There has not yet been a big effort to bring in extra feed or hay. Poultry farmers have indicated that they are using more water as the temperature increases. 

Figure 11. Forest fires in San Sebastian, Puerto Rico. March 3, 2021. Photo credit: José M. Martínez.
Drought-Relevant News in the Region 
The UVI College of Science and Math, Caribbean Green Technology Center in collaboration with UVI Cooperative Extension Service held a community outreach webinar on drought on March 3, 2021. Speakers included Dwayne Petersen, Office of Insular Affairs, US Department of the Interior; Brad Rippey, USDA, Office of the Chief Economist; Royce Creque, Bordeaux farmer from the island of St Thomas; Megan Donovan, Research Assistant, and Dr. Marilyn Swisher, University of Florida. You can watch the webinar here:
For More Information

Prepared By
Odalys Martinez
Senior Service Hydrologist, NWS Weather Forecast Office San Juan

Meredith Muth
NOAA/National Integrated Drought Information System (NIDIS)
William Gould, Nora Alvarez, and Eva Holupchinski
USDA Caribbean Climate Hub, USFS International Institute of Tropical Forestry

Christina Chanes, Gregory Guannel
University of Virgin Islands

Victor Murphy
Climate Services Program Manager, National Weather Service Southern Region

Acknowledgements. Thanks to the Agricultural Extension Service, College of Agricultural Sciences, University of Puerto Rico-Mayaguez. Thanks to Robert Godfrey, Director of the UVI Agricultural Experiment Station and Professor of Animal Science; José Zamora, Fruit Specialist and Professor at UPR Extensión Mayagüez; Harry Ramirez, Finca Hacienda La Paz; and Eric Harmsen, Professor of Agricultural Engineering UPR.
USVI Reporting Input: Several individuals contributed to this report and we are acknowledging the following for their support including the faculty, staff and collaborators of the UVI School of Agriculture, UVI Physics Program, UVI Etelman Observatory, UVI Agricultural Experiment Station, VI Department of Agriculture, UVI Green Technology Center, as well as the USDA Office Chief Economist, National Parks Service in St. Croix, USDA Farm Service Agency, Coral Bay Community Council and the many volunteer drought reporters and farmers from across the territory.     
About This Report

This Drought Update is issued in partnership between the National Integrated Drought Information System (NIDIS), National Oceanic and Atmospheric Administration (NOAA) National Weather Service, and the U.S. Department of Agriculture (USDA) and the University of the Virgin Islands. The purpose of the update is to communicate a potential area of concern for drought expansion and/or development within Puerto Rico and the U.S. Virgin Islands based on recent conditions and the upcoming three month forecast. 

NIDIS and its partners will issue these updates every two months. Subscribe for these U.S. Caribbean drought updates here.