• What can we usually expect during this period?
  • Climatically, September to November forms the second half of the wet season in the Caribbean islands and in Belize. During this period, a large number of wet days and frequent wet spells occur. However, a number of short dry spells still can punctuate this season, particularly in the Greater Antilles.
  • By contrast, the Guianas are in their hot, dry season, running into November in most areas, but continuing through April in far inland, southwestern parts of the region. Hence, frequent dry spells, but infrequent wet days and wet spells are the historical norm from September to November.
  • The 2026 Atlantic Hurricane Season officially lasts until November 30th, with the peak of tropical cyclone activity typically lasting until mid-October, but storms and hurricanes have occurred after the official end date.
  • September and October form the last two months of the Caribbean Heat Season. These months are characterised by higher night- and daytime temperatures, peaking air humidity and a high frequency of hot spells through September in The Bahamas, Belize, the Greater Antilles and the Leeward Islands, through October in the ABC Islands, Barbados, the Guianas, Trinidad and Tobago and the Windward Islands.
  • In the Caribbean islands and Belize, the ground surface and soils become more moisture-laden, often to the point of saturation. When intense showers occur, the potential for flooding, flash floods and associated hazards and impacts such as land slippage, rock fall and soil erosion is particularly high. With a full foliage, potential wind damage related to tropical cyclones is increased. On the bright side, the frequency of Saharan dust incursions and local dust levels should be lower during this period. Access more detailed forecast information on dust and air quality in the Caribbean here: http://dafc.cimh.edu.bb/. In addition, unless flash droughts develop at any point during the peak and tail end of the Heat Season, wildfire potential and the concentration of airborne particulates should be low as well.
  • By contrast, with a peaking frequency of dry days and short dry spells, the ground surface and soils in the Guianas usually lead to a reduction in flood potential (i.e., moderate to high), but an uptick in wildfire potential, the concentration of airborne particulates and local dust levels.
  • On most days, across the region, swells, surges and rip currents tend to be muted compared to other times in the year due to slower winds. However, these hazardous conditions peak during and in the days around the passage of tropical cyclones – even if remotely located. In such cases, they can be particularly hazardous to life and engender beach erosion. (Seven-day forecasts of swell heights may be found here: https://marine.cimh.edu.bb/#/model/WaveWatch%203/Regional).
  • Notwithstanding that it is the wettest part of the year in the Caribbean Islands and Belize, there remains a high risk of skin damage due to intense ultraviolet (UV) light emitted by the sun. The UV index will progressively decrease from extremely high (11-12) to very high (9-10) on sunny days towards November.
• What is different this year?
  • In recent months, temperatures in the equatorial Pacific have warmed at near-record pace, signifying a very strong El Niño which is virtually certain to remain in place throughout the upcoming period and into early 2027.
  • Because El Niño changes the amount of heat in the ocean and atmosphere across the tropics, El Niño typically:
    • increases the chance of drought while decreasing rainfall frequency
      • region-wide: through September or October;
      • in the Lesser Antilles and the Guianas: through the first half of the ensuing dry season;
      • in the Greater Antilles southwards and eastwards of Cuba: there is a less predictable outcome past the month of October.
    • decreases Atlantic Hurricane Season activity – particularly after August. This is mainly because strong winds blow in different directions at different heights (i.e., strong vertical wind shear) are inhibitive to tropical cyclone development most of the time.
    • 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).
  • The September-October-November 2026 outlook In further detail:
    • A lackluster first half of the 2026 Atlantic Hurricane Season – which can to some extent be ascribed to the very strong El Niño conditions – featured only 5 tropical storms with minimal impact to the Caribbean. The lackluster activity is forecast to continue during the second half of the Season. According to the CIMH’s 2026 Hurricane Season Activity Outlook, September to November is predicted to feature fewer storms than usual, i.e., 3 to 8 named storms of which around 2 to 5 may develop into a hurricane, and 1 or 2 becoming a major hurricane (medium confidence). However, while low numbers mean a lower chance of any given location to be impacted, one strong event can be enough to cause catastrophic impacts.
    • The aforementioned El Niño conditions mean less frequent rainshowers, wet spells and heavy rain than is typical during the peak of the Caribbean Wet Season (medium confidence), with increasing drought risk. The latest CariCOF precipitation-related outlooks suggest that seasonal rainfall totals are also likely to be unusually low during the peak of the Wet Season throughout the region, with the highest chances for rainfall deficits in coming months in Hispaniola, Puerto Rico, the US Virgin Islands, the Lesser Antilles, and the ABC Islands (high confidence). More uncertainty exists in Cuba, the Cayman Islands, Jamaica and Guyana, but the forecast still suggests a possibility of unusually low rainfall there (medium confidence).
    • Following an unusually dry first half of the 2026 Wet Season, most islands in the Caribbean are already faced with cumulative rainfall deficits. In view of pre-existing and forecasted rainfall deficits, severe long-term drought at the end of November 2026 is imminent in Saint Lucia (high confidence), is evolving in the ABC Islands, Antigua, the Northern and Northwest Bahamas and Tobago (high confidence), and might possibly develop or continue in Grenada, Martinique, St. Vincent, and the US Virgin Islands (medium confidence). Long-term drought impacting those areas may affect natural freshwater availability across a multitude of sectors where unmitigated by desalination. Be further advised that long-term drought concerns are likely to further expand and intensify into a significant regional drought event from December onwards, i.e., into the 2026-2027 Dry Season.
    • Despite that the upcoming period may not produce the usual amount of rainfall, or the usual frequency of severe weather leading to excessive rainfall events and very wet spells, the upcoming period will still see high (i.e., at least once every other year) to extremely high (i.e., at least once in most years) potential for flooding, flash floods, cascading hazards & impacts throughout the region. 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/).
    • Because the Region expects more clement, sunny weather than usual associated with the evolving El Niño, the Tropical North Atlantic and Caribbean Sea will store unusually large amounts of heat in coming months, and release some of that heat to the overlying atmosphere. Hence, even as trade winds slacken and humidity rises, there are strong indications that the level of excessive heat during the last two months of the Caribbean Heat Season – i.e., September and October – will exceed the norm. Heat stress is, therefore, a particular concern in the Lesser Antilles and the Guianas during the peak of the 2026 Heat Season in September or October. The latest CariCOF Heat Outlook suggests unusually warm daytime and nighttime temperatures, increased humidity, as well as a higher frequency/longer duration of hot spells (high confidence) and the possibility of full-blown heat waves (medium confidence). More heat and heat impact information can be found in the latest Heat Outlook product issued at: https://rcc.cimh.edu.bb/heat-outlook/.
    • Note: 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.

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.