While it may not be officially considered a “heatwave” or hot spell, Trinidad and Tobago is forecast to experience maximum high temperatures not seen for 2021 to date.
As Hurricane Sam moves northeast of the region, a trough extending southwest of the powerful hurricane is forecast to slacken the pressure gradient across the Lesser Antilles, allowing for sunny skies and light winds – the perfect combination for high temperatures.
Rainfall is forecast during the afternoons across western and hilly areas of both islands, bringing much-needed cooling to localized areas of the country. In fact, hotter temperatures may result in stronger convection (i.e. stronger showers and thunderstorms) across Trinidad. Strong/severe thunderstorms with light winds are capable of producing frequent lightning (likely) funnel clouds (possible), waterspouts, tornadoes (unlikely), and even hail (possible, but very low chances).
T&T’s Scoarching Temperature Forecast
In Trinidad, data from Piarco are used as the climate reference site by the TTMS, while in Tobago, data from Crown Point is used for that island. The temperature data recorded (and forecast) at these sites determine the issuance of a Hot Spell Alert/Watch/Warning.
Maximum high temperatures in the below forecast are for those sites. However, it should be noted that hotter temperatures are expected across urbanized areas like San Fernando, Chaguanas, Port of Spain, Scarborough, environs, and along the East-West Corridor.
It is important to note that every day through the next five days, late morning through afternoon showers and possible strong thunderstorms are forecast to develop across the western half and hilly areas of Trinidad, as well as parts of Tobago. Rainfall and high cloud cover will reduce maximum temperatures, possibly below what is forecasted at Piarco and Crown Point.
Through the next five days at Piarco, Trinidad, maximum high temperatures are forecast to range between 33°C and 36.0°C, with peak high temperatures forecast on Monday, September 27th, 2021. Across other areas of Trinidad, maximum high temperatures from 31°C in forested areas to as high as 41°C in urbanized areas, particularly Port of Spain and western areas of the island, are possible with the highest temperatures on Monday.
In Tobago, maximum high temperatures at Crown Point are forecast to range between 32°C and 33°C, with cooler temperatures in forested areas and higher temperatures mainly across western Tobago and urbanized locations.
High environmental temperatures can be dangerous to your body. In the range of 32˚C to 40˚C, you can experience heat cramps and exhaustion. Between 40˚ and 54˚C, heat exhaustion is more likely. You should limit your activities at this range.
The Heat Index
Temps in cities, such as Port of Spain, tend to be much higher than surrounding locations due to a phenomenon called the Urban Heat Island Effect. There are several causes, but the main instigator for this phenomenon tends to be increased dark surfaces such as roads and pavement in cities, which absorb solar radiation more than surrounding areas.
As many may take to social media to complain about the heat, or more so what outside felt like, you may be complaining about the heat index. This feels like temperature is a combination of the actual air temperature and relative humidity, determining what the air feels like to a person, i.e., how hot it actually feels.
The heat index is important because of sweating. Your body sweats to cool the skin and maintain a constant, healthy body temperature. This cooling process means that the sweat has to evaporate off the skin to remove heat. However, if the sweat is unable to evaporate, the body isn’t able to regulate temperature.
With high volumes of moisture in the air, also known as high relative humidity, which T&T regularly experience due to its tropical climate, the rate of sweat evaporation decreased. This is because the atmosphere is unable or has limited potential to hold additional moisture in the atmosphere.
This results in you feeling warmer in humid conditions and cooler in less humid conditions, i.e., when relative humidity decreases. As temperature increases, the heat index increases, and as relative humidity increases, so does the heat index.
The heat index is generally classified into four categories: caution, extreme caution, dangerous, and extremely dangerous. Generally, across Trinidad and Tobago, heat indices will vary between levels that require extreme caution to dangerous levels over the next five days. In urbanized areas like Port of Spain, the heat index may reach levels that are considered extremely dangerous between 10:00 AM and 3:00 PM.
Will this be record heat?
Where will these temperatures stand compared to our records? The hottest recorded in Trinidad, based on data from the Global Historical Climatology Network (pre-1980) and the Trinidad and Tobago Meteorological Service (1991-2020), stands at 37.8°C recorded on April 20th, 1946 at Wallerfield.
If temperatures at Piarco, Trinidad verify above 34.6°C in the coming days, it will become the hottest day for the year to date. At Piarco International Airport, where the new official records began, the hottest temperature for September was recorded on September 25th, 1990, at 36.5°C.
If temperatures at Crown Point, Tobago verify above 32.9°C in the coming days, it will become the hottest day for the year to date. At A.N.R Robinson International Airport, in Crown Point, the hottest temperature for September in the last 30 years was recorded on September 16th, 1989, at 34.2°C.
Why would this not be a heat wave?
For a hot spell (or heatwave) to be declared in Trinidad and Tobago by the Trinidad and Tobago Meteorological Service (TTMS), a period of hot temperatures, characterized by maximum temperatures of at least 34.0°C (above 33.9°C) in Trinidad and 32.0°C in Tobago, must last five or more consecutive days across the country. A short-duration hot spell is three or more consecutive hot days.
It is important to note that the temperature criteria have to be met for both a normal hot spell and a short-duration hot spell for both Trinidad and Tobago. Alerts are not typically issued for short-duration spells from the TTMS.
Based on the current forecast, Trinidad may only exceed the 33.9°C thresholds for four days, while Tobago will meet and exceed the 32.0°C thresholds. Thus, it may not officially be declared a hot spell or heatwave on a technicality, but that should not preclude you from taking precautions.