The Trinidad and Tobago Meteorological Service (TTMS) is officially declaring the start of the 2025 Dry Season today, Tuesday 14th January 2025. The Dry Season occurs once the TTMS observes the following synoptic features:
- The intensification and equatorward migration of the North Atlantic Sub-Tropical High Pressure cell.
- Strengthened Trade-wind inversion (west Africa, central tropical Atlantic and eastern Caribbean)
- Upper-Level Westerly winds.
- Inter-Tropical Convergence Zone (ITCZ) in its southernmost position across the tropical Atlantic Ocean.
The atmosphere over the region has transitioned to its drier state following a gradual transition from the wet into the Dry Season.
During early January, the climatic patterns and features ( a relatively weak North Atlantic Sub-Tropical Pressure cell and strong upper-level easterly winds) had delayed the full formation of the Dry Season. During the last few weeks, there has been an observed reduction in the frequency of showery and/or rainy weather over Trinidad and Tobago resulting from dry season synoptic features, such as passing mid-latitude frontal systems inducing moist low-level perturbations over the region.
The Dry Season generally manifests itself by reduced moisture, increased atmospheric stability, fewer deep clouds, less frequent rainfall events, warm days and cool nights, and a general shift in the surface wind direction from mostly easterlies to north-easterlies.
Although the Dry Season experiences significantly reduced rainfall amounts compared to the Wet Season, it is not devoid of rainfall. The occurrence of rainfall events across Trinidad and Tobago is not expected to be a result of Wet Season systems such as ITCZ, Tropical Waves, or Tropical Cyclone activity but from
Dry Season synoptic features include the passage of induced moist low-level perturbations from mid-latitude frontal systems and convergence bands of clouds over the region.
The recently declared weak La Niña in the central tropical Pacific Ocean is expected to positively influence rain-producing synoptic features in the Dry Season and, therefore, enhance rainfall totals mostly in the early season months of January to March and less so in April and May.
Likely impacts of the 2025 Dry Season:
Initial wetter-than-usual and warmer-than-usual conditions during January, February, and March may result in the following:
- Less vegetative stress due to relatively less surface dryness;
- A positive impact on surface and groundwater recharge and stream flow rates;
- An increase in the breeding areas for insect vectors such as mosquitoes due to uncovered water storage devices and water pooling in drains, low-lying areas and roof guttering;
- A decrease in the potential for bush, forest and landfill fires especially during January to March.
As the dry season progresses from April through May, there is an increased probability of the occurrence of Saharan dust-haze events and increased potential for bush, forest, and landfill fires, contributing to a reduction in air quality. In light of the foregoing, the public is advised to conserve, store, and sustainably manage water. It is highly recommended that the public refrain from burning rubbish in grassy or forested areas during the Dry Season. Relevant agencies and ministries are advised to take measures to mitigate the potential impacts of the Dry Season.
