The Trinidad and Tobago Meteorological Service (TTMS) is forecasting near- to above-average rainfall totals across much of the country for June 2024 in their updated outlook, issued on May 21st, 2024.
June is generally the first month of the annual Wet Season in Trinidad and Tobago. Early-season tropical waves commonly affect the country every five to seven days. Rainfall may occasionally be influenced by the Intertropical Convergence Zone or an early-season Atlantic tropical cyclone.
In the latest outlook, the TTMS says that the 2024 Wet Season is likely to begin with wetter-than-usual conditions across the country. They add that there is a 42% to 63% chance for above-normal rainfall in June for western areas of Trinidad and eastern areas of Tobago, with other areas near normal.
The Madden–Julian Oscillation (MJO) is forecast to enhance cloudiness and rainfall over the southern Caribbean and Trinidad and Tobago throughout June.
For the first week of June, the North Atlantic Oscillation (NAO) is forecast to be positive, but from June 5th through 6th, a negative NAO is forecast through June 26th. A positive NAO increases the chance for strengthened trade winds, enhancing the cooling of sea surface temperatures in the North Atlantic, which generally leads to a decrease in sea surface temperatures and fast-moving showers. However, with a negative NAO forecast for much of June, we could see further warming of sea-surface temperatures and weaker-than-usual winds, which would result in more frequent sea breeze convergence and rainfall across western areas of Trinidad.
Currently, sea surface temperatures in waters surrounding Trinidad and Tobago, including waters to the east of the eastern Caribbean to the West Coast of Northern Africa, are well above average, with most areas near record warmth.
June is the second wettest month of the year for Trinidad and the fifth wettest month for Tobago, with an average (1991-2020) monthly rainfall of 243.3 millimeters at Piarco, Trinidad, and 157.3 millimeters at Crown Point, Tobago.
June is forecast to kick off a wetter-than-usual start to the 2024 Wet Season. According to the TTMS, there is a high chance for most of Trinidad to exceed 250 millimeters of rainfall (the monthly threshold for flooding), particularly in eastern areas, for June 2024, which increases the potential for flood events in those areas. Officially, across both islands, there is a 13% to 93% chance of rainfall exceeding 250 millimeters in June 2024.
In the last 43 years (1981-2023), the driest June recorded 113.1 millimeters at Piarco and 50.3 millimeters at Crown Point in 2009 and 1981, respectively. The wettest June in the same period recorded 457.1 millimeters at Piarco in 1983 and 377.4 millimeters at Crown Point in 1992.
Temperature-wise, the TTMS is still forecasting above-average temperatures for June and over the next several months through the Wet Season.
During June, Trinidad and Tobago can experience hot days (days with maximum temperatures reaching or exceeding 34.0°C in Trinidad and 33.0°C in Tobago), which can likely develop into hot spells (periods of at least five consecutive hot days). Excessive heat build-up is highly likely in urban and built-up areas, especially on hot days.
