• What can we typically 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 hot spells, 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 hot spells 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, the amount of heat in the North Atlantic Ocean and the Caribbean Sea runs above-average. Although sea surface temperatures have cooled considerably from record high values observed from June 2023 through January of this year – thanks to strong cooling breezes from January to April -, they still run above-average in and around the Caribbean.
• The June-July-August 2025 outlook In further detail according to Scenario A (few SAL intrusions):
  • The 2025 Atlantic Hurricane Season officially started on June 1st and is forecast to potentially be intense with a cross-agency consensus estimate of 13-20 named storms (i.e. tropical storm, hurricane or major hurricane) (high confidence), including approximately 6-12 hurricanes, of which 3-5 may easily intensify into a major hurricane (i.e., category 3, 4 or 5 on the Saffir-Simpson scale) (medium confidence) over the entire season. In addition, CIMH predicts between 3 and 10 named storms through the end of August, as compared to 7-13 from September onwards.
  • Seasonal night-time and day-time temperatures in the Caribbean are expected to be at least as warm as usual during the summer portion of the Heat Season 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 hot spells are expected, especially towards August. We expect 25 or more days spent in hot spells for The Bahamas, northern Belize, the Greater Antilles (except some parts of Puerto Rico), St. Croix; 10 to 25 hot-spell days in the wind-sheltered areas of the Lesser Antilles; fewer than 10 hot-spell days in most other locations (medium to high confidence). Importantly, 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 heavy showers are forecast to be at least as high as usual across Cuba, Hispaniola, Puerto Rico, and Guyana, but the usual or less elsewhere (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 in the 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.