• What can we usually expect during this period?
  • Climatically, March to May forms the late Dry Season in Belize and the Caribbean Islands.
  • This season is characterised by relatively few wet days and a small number of wet spells, but many dry days and quite a few dry spells.
  • The resulting drier surface and foliage increase wildfire potential and the concentration of airborne particulates. Local dust levels should also be increasing during prolonged dry spells and towards the end of the dry season.
  • Largely fueled by drier soils, the onset of the Caribbean Heat Season – characterised by the recurrence of heatwaves – typically occurs in April or May. Nonetheless, in recent years, the onset has occurred as early as March (in Belize and Trinidad) or April (elsewhere).
  • In the Guianas, the Greater Antilles and, in some years, the Lesser Antilles, the wet season tends to start in May, with a return of heavy rainfall.
  • In addition, though the 2025 Hurricane Season officially starts on 1 June, tropical cyclones have occurred and are increasingly common before that date, and strong activity can occur very early on in the season.
  • Severe weather systems related to tropical cyclones, as well as heavy showers may affect Caribbean territories repeatedly as early as April or May. Persons should keenly monitor weather advisories issued by the National Meteorological Services and other information provided by the Caribbean Disaster Emergency Management Agency (http://cdema.org/) and the US National Hurricane Center (https://www.nhc.noaa.gov/).
  • The frequency of Saharan dust incursions into the Caribbean tends to increase during this period to reach its annual peak which starts in May. It should be noted that, in some years, significant Saharan dust episodes also occur in March and April. (Access more detailed forecast information on dust and air quality in the Caribbean may be found here: http://dafc.cimh.edu.bb/).
  • UV exposure is set to be dangerously elevated. On a scale from 1 to 12, the UV index on sunny days will be 8-10 (very high) to 11-12 (extremely high).

• What is different this year?
  • This year, high sea surface temperatures in the Tropical North Atlantic Ocean and the Caribbean Sea are expected to persist, though no longer at record values as was the case from June 2023 through January 2025.
  • By contrast, weak La Niña conditions in the tropical Pacific Ocean will more likely than not make way for ENSO neutral conditions – i.e., sea surface temperatures in the Eastern Equatorial Pacific should be near average. As such ENSO conditions are unlikely to exert a strong influence on Caribbean climate in March-April-May 2025.
  • Years in which Atlantic ocean temperatures are high typically drive (1) an uptick in excessive, humid heat in the Caribbean to the point of significant heat stress in the Heat Season; (2) an early and often rapid transition into the wet season – this year particularly in Barbados, Trinidad and Tobago and the Windward Islands – with frequent, heavy showers triggering episodes of flooding and flash floods; and (3) potentially, an early onset of an active Atlantic Hurricane Season.
  • The timing of the start and the intensity of the wet, heat and hurricane seasons will ultimately depend on the frequency of atmospheric patterns that either are conducive to or suppress ‘deep convection’ – i.e., strong vertical updraughts of hot and mostly humid air, driving severe weather.
    One well-known example of suppressive conditions is the frequency of intrusion of very dry (and, at times, dust-laden) air from the Sahara higher up in the atmosphere, the so-called ‘Saharan Air Layer’ or SAL.
  • If SAL intrusions end up more frequent than usual, 2025 will be even hotter & more humid, often with hazy By contrast, more Saharan air intrusions also translate to more erratic tropical cyclone and other severe weather activity, reduced potential for flooding, flash floods and associated hazards and impacts. Furthermore, any ongoing drought concerns may be prolonged, with increased wildfire potential and frequency of dry spells. The exact timing of these Saharan air intrusions is not predictable at the seasonal timescale, but weather forecasts (up to 7 days in advance) can easily pick these up. It is, therefore, recommended that stakeholders pay close attention to the local weather forecasts as it pertains to haze and dust.

• In light of the warmer than usual North Atlantic, the forecast for March-April-May 2025 further suggests:
  • Seasonal rainfall amounts are forecast to be the usual or more in the ABC Islands, the Guianas, the Lesser Antilles, Hispaniola and the US Caribbean Territories, but, likely, the usual or less in The Bahamas and Cuba (medium confidence).
  • Short-term drought is expected to be a significant concern by the end of May 2025 in the northern Bahamas and in Grand Cayman (medium to high confidence), but also possible in the central Bahamas, western Cuba, and Jamaica (medium confidence). Short-term drought may impact food production, water quality and quantity from small streams, small ponds and other surface sources.
  • Long-term drought is expected to be a significant concern by the end of May 2025 in the northern Bahamas and southwest Belize (high confidence) and might possibly develop or continue in the ABC islands, the central Bahamas and southeast Puerto Rico (medium confidence). Long-term drought (on a 12 months timescale) affects water availability across a multitude of socio-economic sectors in countries where the main freshwater resource is from very large rivers, large reservoirs or groundwater.
  • Night-time (minimum) temperatures are forecast to be higher than usual in most areas (medium to high confidence). In addition, daytime (maximum) temperatures will likely be as high as usual or higher, with the exception of the area from Haiti eastwards to the Leeward Islands. Episodes of hazardous heat could appear in April & May, with increased risk in locations that are wind-sheltered and/or in drought

This Bulletin provides a broad overview of climate conditions up to 3 months in advance. It is based on insights drawn from CIMH’s suite of technical climate information products and epidemiological insights from CARPHA and PAHO. The information contained herein is provided with the understanding that the CARPHA, the PAHO and the CIMH make no warranties, either expressed or implied, concerning the accuracy, completeness, reliability or suitability of said information. The Bulletin may be freely used and disseminated by the public with appropriate acknowledgement of its source but shall not be modified in content and then presented as original material.