• What can we usually expect during this period?
  • Climatically, June to August forms the summer part of the Caribbean Heat season, the first half of the wet season in Belize and the Caribbean Islands, as well as the first half of the Atlantic Hurricane Season. All of these should reach their annual peak by the end of August.
  • This period is characterised by higher night- and daytime temperatures, increasing air humidity and tropical cyclone activity, a significant increase in the frequency of heatwaves, wet days and wet spells, but a decrease in the number of dry days and dry spells compared to March to May. However, in portions of the Greater Antilles, a drier period of about 3-6 weeks tends to break up the wet season into two parts.
  • As the ground surface and foliage become more moisture-laden, wildfire potential, the concentration of airborne particulates and local dust levels should decrease during June.
  • In the Guianas, the primary wet season tends to end in early-August. Until then, the frequency of heavy rain showers should remain steady. As the primary dry season sets in later in August, temperatures should increase and the first heatwaves may occur as rainfall and moisture levels decrease.
  • The frequency of Saharan dust incursions into the Caribbean tends to peak until July and slowly decrease from August onwards. 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 11-12 (extremely high) throughout the period.
• What is different this year?
  • This year, an El Niño event ended to likely make way for its cold counterpart in the tropical Pacific Ocean, namely a La Niña, by June-July-August.
  • In the North Atlantic Ocean and the Caribbean Sea, (near-) record high sea surface temperatures are expected to prevail.
• The June-July-August 2024 outlook In further detail according to Scenario A (few SAL intrusions):
  • The 2024 Atlantic Hurricane Season officially started on June 1st and is forecast to be hyperactive with a cross-agency consensus estimate of 23-29 named storms (i.e. tropical storm, hurricane or major hurricane) (high confidence), including approximately 11-13 hurricanes (medium confidence), of which 5-7 may easily intensify into a major hurricane (i.e., category 3, 4 or 5 on the Saffir-Simpson scale) (high confidence) over the entire season. In addition, CIMH predicts between 7 and 14 named storms through the end of August, as compared to 13-19 named storms from September onwards.
  • Seasonal night-time and day-time temperatures in the Caribbean are expected to be even warmer than usual and accompanied by high levels of air humidity (high confidence). Significant episodes of heat stress are likely to become more prevalent and persistent towards the peak of the Heat Season in August (and September).
  • Frequent and persistent heat waves are expected, especially towards August. 50 or more heatwave days in The Bahamas, Barbados, Dominica, 20-40 heatwave days in Belize, Greater Antilles, Trinidad & Tobago and wind-sheltered areas of the Windward Islands (medium to high confidence). In the aftermath of a debilitating severe weather event, exposure to the combination of humid heat and recurrent heat waves can become severely dangerous to human life if unmitigated.
  • Seasonal rainfall amounts, as well as the frequency of light and heavy showers are forecast to be higher than usual in an intense 2024 Caribbean Wet Season (medium to high confidence). While beneficial for drought relief and recharge of water reservoirs, heavy rains lead to high to extremely high potential for flooding, flash floods, cascading hazards & impacts (except ABC Islands). (medium to high confidence).
  • In line with the forecasted intense wet season, drought concerns by the end of August in the Caribbean are few.

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.