Is a "Feels Like 46°C" the New Normal? Reasons for the Prolonged Heatwave in the Caribbean

Is a "Feels Like 46°C" the New Normal? Reasons for the Prolonged Heatwave in the Caribbean

"It's not that the heat has increased," but "the shape of heatwaves has changed"

The Caribbean Sea, with its tropical sea breeze, strong sunlight, and image as a tourist paradise, has seen a qualitative change in "heat" over the past 50 years. Recent research reports that extreme heatwaves in the Caribbean region have been increasing in frequency, duration, and intensity. Moreover, the impact is more pronounced not only in coastal resorts but also in urban areas with concentrated populations.


This study is not just looking at peak temperatures. It uses an index that includes the "perceived" discomfort for humans (heat index), highlighting the increase in "danger zones" not only during the day but also at night. The heat is not coming as an "event" but is beginning to raise the baseline of urban life.


What is called an "extreme heatwave": The 95th percentile threshold

The research team analyzed temperature and climate records from 1971 to 2025, tracking changes in the frequency, duration, and intensity of heatwaves. Notably, they define "extreme heat" as days when both the maximum and minimum heat index exceed the 95th percentile. This means that the heat persists not only during the day but also at night.


The results were clear. In major cities like Havana, Santo Domingo, San Juan, and Port-au-Prince, there is a trend of increasing heatwave days by up to about 3 days per decade. It may seem like just a few days, but urban heat impacts all aspects of society, including emergency transport, power outages, labor productivity, tourism, and education, as "delayed damage."


In recent cases, the maximum perceived temperature has reportedly exceeded 115°F (about 46°C). Since the heat index is affected by humidity, the burden on the body can increase more than the temperature itself.


Why the Caribbean is vulnerable to heatwaves: The fear of "decreasing clouds"

The research team leading the study points out that the Caribbean is vulnerable to extreme heat due to strong solar radiation and the fact that clouds decrease during heatwaves, increasing the solar energy reaching the surface. A heatwave is completed not only by "hot air" but also by "clear skies that burn."


Moreover, since the heat index is based on the assumption of "shade and light wind," the perceived temperature can rise even higher under direct sunlight (it can increase by up to 15°F as a guideline). In the outdoor environment of the Caribbean, this "increase" raises the real danger level.


Global warming + El Niño's "add-on": The difference between years with more heatwaves and those without

The main cause of the increase is, of course, the global rise in temperatures. The study shows that much of the increase in heatwaves is linked to warming, while also touching on El Niño as a factor explaining annual fluctuations. During El Niño phases, when sea surface temperatures are higher, heatwaves become more frequent, with the possibility of increasing heatwave days by about 2 days per season.


The fear here is that when the "average elevated by warming" is compounded by "El Niño's add-on," society's coping capacity (hospitals, electricity, transportation, school, and workplace regulations) quickly approaches its limits. Extreme events appear not as an "extension of the average" but as a "destruction of the margin."


Health risks are not just "heatstroke": They affect the heart, kidneys, and chronic conditions

The impact of extreme heat is not a simple choice between collapsing or not. The WHO has organized that in environments where body temperature regulation cannot keep up, the risk of heat exhaustion and heatstroke increases, and the body's efforts to cool down can strain the heart and kidneys, worsening the risk of chronic diseases such as cardiovascular, respiratory, mental, and diabetes.


In the field, signs of heat exhaustion such as "headache, dizziness, nausea, heavy sweating, and fatigue" are more likely to appear, and missing them can lead to accidents. The more regions where heat increases, the more effective symptom awareness and the establishment of "escape routes" become.


Furthermore, the broad framework that climate change is increasing the frequency and intensity of heatwaves is widely indicated by the IPCC. The Caribbean study can be seen as an example of this "global trend" materializing in regional urban life.


Infrastructure and economy: Heat directly impacts electricity and work styles

The prolongation of heatwaves shakes not only lives but also the foundation of living. Increased demand for air conditioning puts a strain on the power grid, and if a blackout occurs, air conditioning stops—a vicious cycle emerges. The research introduction also touches on researchers' involvement in safety monitoring of power transmission equipment exposed to extreme weather, showing a structure that doesn't end with "heat = health problem."


In terms of labor, measures against heat stress are becoming increasingly important worldwide. The WHO and WMO point out that increased heat stress affects workers' health and productivity and have issued guidance on measures.


What is needed now is not "spirit" but "preparation": Realistic measures to combat urban heat

Researchers emphasize the need to urgently strengthen monitoring, invest in heat mitigation measures, and community education.

So, what can municipalities, companies, and individuals start with? Realistically, the following "accumulation" is effective.

  • Visualizing heat: Alert information including heat index and nighttime heat, and dissemination of evacuation sites (cooling centers)

  • Reducing urban heat: Creating shade, planting street trees and rooftop greenery, heat-reflective paving, and cool roofs

  • Preparing for power outages: Backup power for hospitals, shelters, and communications, priority restoration plans for vulnerable areas

  • Updating work styles: Adjusting outdoor work hours, break rules, standardizing hydration and salt intake


If heatwaves are dealt with "when they come," we lose. If designed with the premise that they will come, the damage can be reduced. This shift is becoming the standard equipment for a world where warming is progressing, not just in the Caribbean.


Reactions on social media (within observable range)

  • Researcher's post (Instagram): The lead author reports the publication of a new paper, expressing gratitude to those involved and sharing the DOI with readers. The intention to expand the research findings as "useful knowledge in the field" can be inferred.

  • Community support (LinkedIn): When the same researcher reports the presentation and award of Caribbean extreme heat research, the comments section is filled with congratulations such as "proud" and "congratulations," showing interest in the research theme and a supportive atmosphere for human resources.

  • "Not a future issue" resonates: The research introduction strongly conveys the message that "extreme heat is not a future risk but is already rapidly increasing," becoming a shared point of crisis awareness.


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