6-Day Hot Spell Recorded Across T&T

Over the last two weeks, a high-pressure system has dominated conditions across Trinidad and Tobago, with light winds due to tropical cyclones north and east of the region. Over the last 6 days, mostly sunny and hot temperatures across both islands met the threshold for a hot spell or heatwave.

What is a hot spell?

For a hot spell 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, lasting five or more consecutive days. A short-duration hot-spell is three or more consecutive hot days.

It is important to note that for a hot spell, both a normal spell and a short-duration hot spell, the temperature criteria had to be met for both Trinidad and Tobago. We typically don’t see these alerts issued for short duration spells from the TTMS either.

This Week’s High Temperatures

On September 26th, 2020, even with the isolated showers and thunderstorms across Eastern and Southern Trinidad, record high temperatures were recorded across parts of Trinidad and Tobago. Across Trinidad, temperatures ranged between 32°C and 35°C, with urbanized areas seeing hotter temperatures up to 38°C. In Tobago, maximum temperatures generally remained between 33°C and 35°C.

In fact, across both climate reference stations for Trinidad (Piarco) and Tobago (Crown Point), the hottest temperature for 2020 was recorded at 34.9°C and 33.7°C respectively.

Maximum high temperatures recorded across Trinidad and Tobago using a combination of personal automated weather stations and weather stations from the Trinidad and Tobago Meteorological Service (TTMS) on Saturday 26th September 2020.
Maximum high temperatures recorded across Trinidad and Tobago using a combination of personal automated weather stations and weather stations from the Trinidad and Tobago Meteorological Service (TTMS) on Saturday 26th September 2020.

However, with light winds and relatively high humidity, the temperature you feel outside, or the heat index, was much higher. Across Trinidad and Tobago, heat indices were in the danger category, between 40°C and 51°C. This meant that heat cramps and heat exhaustion were likely, with heatstroke probable with continued activity outdoors.

Maximum heat indices recorded across Trinidad and Tobago using a combination of personal automated weather stations and weather stations from the Trinidad and Tobago Meteorological Service (TTMS) on Saturday 26th September 2020.
Maximum heat indices recorded across Trinidad and Tobago using a combination of personal automated weather stations and weather stations from the Trinidad and Tobago Meteorological Service (TTMS) on Saturday 26th September 2020.

Hot temperatures were recorded across both islands on Wednesday has heat persisted over the last ten days. Across Trinidad, temperatures ranged between 32°C and 35°C, with urbanized areas seeing hotter temperatures up to 36°C. In Tobago, maximum temperatures generally remained between 32°C and 33°C.

Maximum high temperatures recorded across Trinidad and Tobago using a combination of personal automated weather stations and weather stations from the Trinidad and Tobago Meteorological Service (TTMS) on Wednesday 23rd September 2020.
Maximum high temperatures recorded across Trinidad and Tobago using a combination of personal automated weather stations and weather stations from the Trinidad and Tobago Meteorological Service (TTMS) on Wednesday 23rd September 2020.

However, with light winds and relatively high humidity, the temperature you feel outside, or the heat index, was much higher. Across Trinidad and Tobago, heat indices were in the danger category, between 40°C and 51°C. This meant that heat cramps and heat exhaustion were likely, with heatstroke probable with continued activity outdoors.

Maximum heat indices recorded across Trinidad and Tobago using a combination of personal automated weather stations and weather stations from the Trinidad and Tobago Meteorological Service (TTMS) on Wednesday 23rd September 2020.
Maximum heat indices recorded across Trinidad and Tobago using a combination of personal automated weather stations and weather stations from the Trinidad and Tobago Meteorological Service (TTMS) on Wednesday 23rd September 2020.

T&T’s Scoarching Temperatures

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 recorded at Piarco, Trinidad by the Trinidad and Tobago Meteorological Service over the last 10 days. The hot spell threshold wave met on the island between September 14th through 16th and again on September 21st through September 26th
Maximum high temperatures recorded at Piarco, Trinidad by the Trinidad and Tobago Meteorological Service over the last 10 days. The hot spell threshold wave met on the island between September 14th through 16th and again on September 21st through September 26th.

There have been two periods over the last two weeks where temperatures at Piarco have met the hot spell threshold of a maximum high temperature of 34.0°C (above 33.9°C) for the island. These periods occurred between September 14th through September 16th, and again September 21st and September 26th. Notably, during both periods, Trinidad recorded (and then tied) its highest maximum temperature for 2020. These hot temperatures have been due to mostly sunny days; light winds all resulting from a high-pressure system at the surface to mid-levels of our atmosphere.

Maximum high temperatures recorded at Crown Point, Tobago by the Trinidad and Tobago Meteorological Service over the last 10 days. The hot spell threshold was met on the island between September 15th through 18th and again on September 20th through September 26th.
Maximum high temperatures recorded at Crown Point, Tobago by the Trinidad and Tobago Meteorological Service over the last 10 days. The hot spell threshold was met on the island between September 15th through 18th and again on September 20th through September 26th.

Similar to Trinidad, Tobago has also recorded two periods where temperatures at Crown Point has met the hot spell threshold of a maximum high temperature of 32.0°C for the island. These periods occurred between September 15th through September 18th, and again September 20th and September 26th.

While both islands have and continue to, experience hot spell conditions, only from September 21st to present the country as a whole has experienced a hot spell (heatwave). This is due to the country (both islands) meeting the threshold for a hot spell advisory to be issued by the Trinidad and Tobago Meteorological Service. A hot spell alert, watch or warning was not issued by the TTMS.

Is this record heat?

Highest maximum high temperatures in Trinidad for 2020 (year-to-date)
Highest maximum high temperatures in Trinidad for 2020 (year-to-date)

Where do 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 (1980-2019) stands at 37.8°C recorded on April 20th, 1946 at Wallerfield.

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.

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.

Several persons across the country took to social media to complain about the heat, or more so what outside felt like. This is called the heat index and is a combination of 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. As relative humidity increases, so does the heat index.

 Heat Index Values Explained
Heat Index Values Explained

Heat index is generally classified into four categories: caution, extreme caution, dangerous, and extremely dangerous. Generally, across Trinidad and Tobago, through Friday, dangerous heat indices are forecast.

Very High Temperatures Ends (For Now)

On Sunday through Monday, a weak tropical wave (Tropical Wave 51) is forecast to traverse the region, bringing cloudy skies with isolated to scattered showers and thunderstorms. On Saturday, much of the activity remained across Southern and Eastern areas.

The heat will continue on Tuesday, but it will be short-lived, as Tropical Wave 52 and the ITCZ are forecast to keep temperatures on the cooler side through the end of next week.

In the Trinidad and Tobago Meteorological Service’s (TTMS) Rainfall and Temperature Outlook for Trinidad and Tobago, issued on September 1st 2020, hotter days are in the forecast.

Usually, the peak of Trinidad and Tobago’s heat season runs from August to October. In most years, September is the hottest month. August through October 2020 is likely to be warmer than usual, with both day and night temperatures expected to exceed their averages. There are concerns for an increase in the number of hot days, and short duration hot-spells remain elevated for September and early October (hot days: days with a maximum temperature greater than 33.9°C in Trinidad and greater than 32.0°C in Tobago.

“There is a greater than 70 % chance for day maximum and night minimum temperatures to be above average, with September and October days and nights likely to be the warmest during the period,” based on the TTMS’s outlook.

Heat Safety

Graphic: Beat the Heat. Heat related deaths are preventable.

Graphic: Beat the Heat. Heat related deaths are preventable.

Source: MEMA
Heat Safety Tips and Resources
Heat Safety Graphic. Source: Heat Safety Tips and Resources

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