News Releases

UWI-led research sheds new light on the Caribbean rainy season

For Release Upon Receipt - August 28, 2020


A paper entitled Seasonal Atmospheric Transitions in the Caribbean basin and Central America, led by a UWI Scientist, recently published in international journal, Climate Dynamics provides new insights into the onset and end dates of the Caribbean rainfall season.  

The Caribbean has a rainfall season that roughly spans May through November with a short dry period in between. The regional agricultural sector is acutely aware of this cycle and in many countries farmers try to estimate the start and end dates of each season to maximize crop production. However, Dr Isabelle Gouirand, Climate Specialist at The UWI, Cave Hill Campus has led a study with collaborators Professor Vincent Moron from Aix-Marseille University, France and Dr Bernd Sing, also from Cave Hill, to help determine exactly when the rainy season will start and end and what atmospheric and oceanic conditions may prompt this. 

Using a new methodology based on “snap shots” of daily weather types associated with either dry or wet conditions, Dr Gouirand and collaborators determined the historical transition between the dry and wet seasons in the Caribbean. They found that the average dates of transition for the 1979-2017 period occur around May 13 (+/- 9 days) for onset, and October 26 (+/- 12 days) for demise.   

They also found that onset in May is rather abrupt, with a sudden increase in the daily rainfall amount over the Caribbean region, with any of a number of atmospheric and oceanic triggers capable of causing onset. In comparison, demise in October is smoother and associated with a gradual rather than a sharp decrease in the daily amount of rainfall.  

An anomalously warm Eastern Pacific Ocean along with an anomalously cold Tropical North Atlantic, Caribbean Sea and Gulf of Mexico can force an earlier end of the rainy season. Importantly, onset and demise are also found to be independent.  This means that a delayed or advanced onset in May does not necessarily translate into a delayed or advanced demise in October.  

The paper also explores the predictability of onset, with predictability in May being low (up to two weeks before the transition) but with significantly greater predictability for the end of the season. This is of particular significance for all rainfall-dependent sectors in the Caribbean (e.g. agriculture, water, tourism etc.). If operationalised, the methodology will enable better determination of exactly when the rain will start and end.



Note to the Editor 

Dr Isabelle Gouirand is a Senior Lecturer in the Department of Biological and Chemical Sciences (The UWI, Cave Hill) and a member of the Caribbean Climate Modellers Consortium co-coordinated by the Climate Studies Group, Mona (The UWI, Mona). Dr Bernd Sing is a Lecturer in the Department of Computer Science, Mathematics and Physics (The UWI, Cave Hill). 

To read the paper published on August 11, 2020: 


About The UWI 

For over 70 years The University of the West Indies (The UWI) has provided service and leadership to the Caribbean region and wider world. The UWI has evolved from a university college of London in Jamaica with 33 medical students in 1948 to an internationally respected, regional university with near 50,000 students and five campuses: Mona in Jamaica, St. Augustine in Trinidad and Tobago, Cave Hill in Barbados, Five Islands in Antigua and Barbuda and an Open Campus. As part of its robust globalization agenda, The UWI has established partnering centres with universities in North America, Latin America, Asia, Africa and Europe including the State University of New York (SUNY)-UWI Center for Leadership and Sustainable Development; the Canada-Caribbean Institute with Brock University; the Strategic Alliance for Hemispheric Development with Universidad de los Andes (UNIANDES); The UWI-China Institute of Information Technology, the University of Lagos (UNILAG)-UWI Institute of African and Diaspora Studies; the Institute for Global African Affairs with the University of Johannesburg (UJ); The UWI-University of Havana Centre for Sustainable Development; The UWI-Coventry Institute for Industry-Academic Partnership with the University of Coventry and the Glasgow-Caribbean Centre for Development Research with the University of Glasgow. 

The UWI offers over 800 certificate, diploma, undergraduate and postgraduate degree options in Food & Agriculture, Engineering, Humanities & Education, Law, Medical Sciences, Science & Technology, Social Sciences and Sport.  

As the region’s premier research academy, The UWI’s foremost objective is driving the growth and development of the regional economy. The world’s most reputable ranking agency, Times Higher Education, has ranked The UWI among the top 600 universities in the world for 2019 and 2020, and the 40 best universities in Latin America and the Caribbean for 2018, 2019 and 2020. The UWI has been the only Caribbean-based university to make the prestigious lists.  For more, visit

(Please note that the proper name of the university is The University of the West Indies, inclusive of the “The”, hence The UWI.)