On Saturday, April 4th, 2020, hot temperatures were prevalent across Trinidad and Tobago.
Across most of the country, temperatures between ranged between 31.0°C and 34.0°C, with isolated areas between 33.0°C and 36.0°C, mainly across Trinidad. In urban areas and areas where development is prevalent, temperatures soared above 35.0°C.
In Port of Spain, at 12:00 PM, a personal weather station (PWS) recorded a temperature of 37.7°C. In Longdenville, near the built-up borough of Chaguanas, another PWS recorded a temperature of 35.3°C this afternoon.
Temperatures 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.
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. Today’s official maximum high at Piarco was 33.5°C.
The Heat Index
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 in order 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 is generally classified into four categories: caution, extreme caution, dangerous and extremely dangerous. Generally across Trinidad and Tobago, we experience heat indices of caution to extreme caution in times of hot days, with isolated areas experiencing dangerous heat indices such as urban areas.
Today’s High Heat Indices
On Saturday 4th April 2020, high heat indices were prevalent across Trinidad and Tobago. Across most of Trinidad and Tobago, heat indices between ranged between 36.0°C and 40.0°C. In urban areas and areas where development is prevalent, the heat index soared to 48.0°C – dangerous levels. At this level, heat cramp and heat exhaustion are likely. Heatstroke becomes probably with strenuous outdoor activity.
High Temperatures To Continue Through April & May
In the short term, a high pressure system is forecast to continue dominating weather conditions through the next 1-2 weeks. This overall setup has also created a favorable wind regime for Saharan Dust to stream across the region.
High pressure systems bring generally dry and stable weather, with sunny skies. This in turn results in higher daytime and afternoon temperatures.
Looking towards the longer term, April and May are two of our warmest months of the local heat season. In the Trinidad and Tobago Meteorological Service’s (TTMS) Rainfall and Temperature Outlook for Trinidad and Tobago, issued on Thursday 2nd April 2020, they expect this pattern to continue in 2020.
In fact, according to the TTMS, the “average day-time maximum and night-time minimum temperatures are very likely to be warmer than average for all of Trinidad and Tobago.” There are also enhanced chances for hot days (34.0°C in Trinidad, 32°C in Tobago) and hot spells.
On through the next 5 days, maximum high temperatures are forecast to be near 32-34°C across Trinidad, and 31-33°C across Tobago. Heat indices are also forecast to be high, near 36-38°C across Trinidad, and 34-35°C across Tobago. Remember, heat indices will be higher in urbanized areas.
Is this a heatwave?