Most of the features which account for the variability of temperature and rainfall in Trinidad and Tobago originate in the tropics, but global features also impact the climatic variability. Phenomena such as El Niño-Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO) are two of the major drivers of climate variability in Trinidad and Tobago. It has also been shown that the Madden-Julian Oscillation (MJO), the Saharan Air layer (SAL), tracks taken by tropical storms, migratory behaviour of the Inter-tropical Convergence Zone (ITCZ) and behaviour of the North Atlantic Sub-Tropical High (NASH) also influence the climate variability in Trinidad and Tobago.

Studies have shown that the El Nino phase of the ENSO modifies the annual cycle of rainfall over the Caribbean greatest, with varying results for different areas. The relationship between El Nino and the rainfall cycle starts with a drying trend during the latter half of the wet season which continues into the dry season and ends with a strong wet signal during the earliest period of the new wet season; this relationship was observed in Trinidad and Tobago during the 2009-2010 episode of the most recent El Nino event. With regards to La Nina, it has been found that the Southern Caribbean including Trinidad and Tobago exhibits wetter than normal late wet season and dry season; while the early wet season at the end of a La Nina event is drier than normal. The link between the NAO and Caribbean rainfall is found in the relationship between pressure systems and rainfall and temperatures in the region. A positive index is indicative of anomalously high pressures across the region resulting in a reduction in rainfall since higher pressure introduces stronger winds, more evaporation, cooler Sea Surface Temperatures (SST's), and less ascending motion. When the index is negative, rainfall in the early period of the wet season is enhanced since lower anomalous pressure introduces lighter winds, less evaporation, warmer SST's, and more ascending motion.