• 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.
  • In the Caribbean Islands and Belize, 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 along the Wet Season, wildfire potential, the concentration of airborne particulates and local dust levels should decrease during June.
  • The frequency of Saharan dust incursions into the broader 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/.
  • 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.
  • 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 is unfolding and strengthening in the tropical Pacific Ocean, meaning ocean temperatures in the eastern Tropical Pacific are substantially warmer than average. This year’s event is likely to be classified as strong or even very strong and is forecast to last at least until early 2027.
  • Unless ocean temperatures in and around the Caribbean are (near-)record warm, strong El Niños typically are the dominant driver of climate variability between different years in the Caribbean.
  • By changing the amount of heat in the ocean and atmosphere across the tropics, El Niño:
    • increases the chance of drought while decreasing rainfall frequency – particularly in the Lesser Antilles and the Guianas, but only during summer in The Bahamas and the Greater Antilles,
    • decreases Atlantic Hurricane Season activity – particularly after August,
    • increases the number of hot and sunny days – with the year after the onset of a strong El Niño often ending up with (near-) record heat,
    • and increases the chance for an early, abrupt onset to the wet season in the year after the El Niño starts (i.e., in 2027).

*Because El Niño can spark multiple episodes of climate extremes in many regions of the world, health practitioners are advised to consult official sources of El Niño (and La Niña) monitoring and forecast information, such as the CARPHA/PAHO/CIMH Health-Climatic Bulletin found at https://rcc.cimh.edu.bb/caribbean-health-climatic-bulletin/ or the WMO El Niño/La Niña Updates found at https://community.wmo.int/site/knowledge-hub/programmes-and-initiatives/climate-services/wmo-el-ninola-nina-updates).

• • Meanwhile, in the North Atlantic Ocean, the amount of ocean heat contained around the northern Caribbean runs above-average, adding heat and humidity to the atmosphere particularly over The Bahamas, Cuba and Jamaica.
  • Ocean heat fuels intense shower and tropical cyclone activity. Hence, unseasonably warm waters around the northern Caribbean may increase the chance for development and rapid intensification of storms. By contrast, chances of significant tropical cyclone activity early in the Hurricane Season is reduced in the Lesser Antilles where water temperature is cooler than its been in recent years, with very low risk of a record-early category 4 or 5 hurricane like Hurricane Beryl.

• The June-July-August 2026 outlook in further detail:
  • The 2026 Atlantic Hurricane Season (which officially starts June 1st and ends November 30th) is forecast to potentially be less intense (with irregular bouts of activity) with an estimated 8-16 named storms (i.e. tropical storm, hurricane or major hurricane), including approximately 3-7 hurricanes, of which around 1-3 may intensify into a major hurricane (i.e., category 3, 4 or 5 on the Saffir-Simpson scale) over the entire season (medium to high confidence).
  • However, from June to August (i.e., the first half of the Atlantic Hurricane Season), CIMH predicts 3-10 named storms compared to the historical average of 5 (medium confidence). And, with the waters around Cuba, the Bahamian archipelago and north of the Greater Antilles being unseasonably warm, the possibility of rapidly intensifying storms is of particular concern in the northern Caribbean. Indeed, devastating hurricanes have tracked through The Bahamas in 1965 (Betsy) and in 2015 (Joaquin) which occurred during strong and very strong El Niño years, respectively.
  • 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 increasingly 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, with a strong increase in the number of days spent in hot spells compared to the historical average anywhere north of 18°N. Thirty or more hot-spell days are likely in The Bahamas, Cuba, Jamaica, St. Croix (high confidence). In comparison, a moderate increase in hot-spell days is forecast for Barbados, central & south Belize, the coastal Guianas, Trinidad & Tobago, and the Windward Islands (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.
  • Consistent with El Niño conditions in this period, seasonal rainfall amounts and shower frequency are forecast to likely be the usual or less across the Caribbean Islands and Belize (medium to high confidence), but at least the usual in French Guiana (low confidence).
  • In spite of remnant dryness in several island nations of the Lesser Antilles at the time of writing, the forecasted rainfall amounts through August should be sufficient to remove widespread short-term drought impacts to soil moisture, stream and small river flow, as well as surface water reservoirs by the end of August throughout most of the region. However, long-term drought – impacting large river flow, very large surface water reservoirs and underground aquifers – is evolving in Saint Lucia and might possibly continue in Martinique and St. Kitts by the end of November.
  • Whereas the wet season rains are beneficial for drought relief and recharge of water reservoirs, the very high chance of occurrence of excessive rainfall events leads to high to extremely high potential for flooding, flash floods, cascading hazards & impacts (except in the ABC Islands) (medium to high confidence).

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.