Trinidad and Tobago Climate
Trinidad and Tobago’s close proximity to the equator enables the country to have two climate
types producing two opposing seasons. These seasons are differentiated by distinct dry and wet
season regimes. The dry season which occurs during January to May is symbolized by a tropical
maritime climate that is characterized by moderate to strong low level winds, warm days and
cool nights, with rainfall mostly in the form of showers due to daytime convection. A modified
moist equatorial climate characterized by low wind speeds, hot humid days and nights, a
marked increase in rainfall which results mostly from migrating and latitudinal shifting
equatorial weather systems, symbolizes the wet season during June to December. The periods
late May and December are considered as transitional periods to the wet and dry seasons
respectively. Variations in these two climatic seasons between the islands of Trinidad and
Tobago are primarily as a result of difference in land size, orography, elevation, orientation in
terms of the trade winds and geographical location. Within the wet season is the hurricane
season which runs from June to November, peaking between August and October. Trinidad’s
geographical location puts it on the southern periphery of the North Atlantic hurricane basin.
As such, Trinidad is not affected directly by storms as frequent as Tobago; however, peripheral
weather associated with the passage of tropical storm systems impacts Trinidad and Tobago
similarly.
Trinidad and Tobago’s daily temperature cycle is more pronounced than its seasonal cycle. The
long term mean (1971 – 2000) annual maximum and minimum temperatures are 31.3 ⁰ C and
22.7 ⁰ C respectively with a mean daily temperature of 26.5 ⁰ C. Generally, the wet season
temperatures are warmer than the dry season temperatures with September being the
warmest wet season month and March the warmest in the dry season. Annually and seasonally
Trinidad is wetter than Tobago; however, the rainfall pattern in both islands display a distinct
bi-modal behavior with early (June) and late(November) rainfall season maxima occurring.
Trinidad’s primary rainfall mode occurs in June while Tobago’s primary mode occurs in
November.
The annual rainfall totals are largely driven by multiple competing weather features, chief of
which are the latitudinal position and strength of the North Atlantic Sub-Tropical High (NASH)
pressure cell, meridional shift of the Inter-Tropical Convergence Zone (ITCZ), westward
propagating Tropical Waves and cyclones (depression, storms, hurricanes), Mid-Atlantic upper
level trough system, localized sea-breeze effects, cloud clusters driven by large scale low level
convergence and orography. Generally, during the dry season the NASH pressure cell center
migrates more southerly than during the wet season and expands equator-ward resulting in
generally subsiding air, low level moisture evacuation and strong trade winds over Trinidad and
Tobago, which result in a drier state of the atmosphere. Usually during May, the slow but sure
shifting of the NASH pole-ward with winds on its southern flank converging more, allows rain
bearing systems such as the ITCZ and Tropical waves to penetrate northward and eastward;
resulting in the transition to and eventual onset of the wet season regime.