Seasonal Forecast: June to August 2021

Date of Issue: June 1st, 2021


Ø Seasonal Forecast: June- July-August 2021 (JJA)


June 1st marks the official start of the Atlantic hurricane/ wet season which ends officially on November 30th each year.  Normally, an increase in the frequency and intensity of rainfall events becomes evident during the first half of the wet season. This year, the first half of the wet season (JJA) is forecast to accumulate less than to the usual amounts of rainfall. At least one 7-day dry spell is possible during June to July. A wetter pattern is expected by August. At least two extreme 3-day wet spells are anticipated and this may increase the chances of flash floods and its associated hazards. At this time, the second half of the wet season (September- November) is expected to be at least as wet as usual. Keep Updated.



Warmer than to usual daytime highs are expected throughout the wet season. During the first half of the wet season, night-time lows along the west coast are anticipated to be slightly warmer than to usual while the east coast and the interior may experience slightly cooler to the usual temperatures.

Generally, an increase in temperatures is expected to continue into the peak of the heat season (August -September). There is a 90% chance that at least 5 consecutive hot days (Hot day; when daily highs are equal to or exceeds 32.9°C at Canefield and 31.5°C at Douglas-Charles) may occur in June. Between July to September there is an 80% chance of having at least 15 consecutive hot days and a 60% chance of at least 30 consecutive hot days. Heat stress may appear and could peak during prolonged heat waves (Heat wave; three or more consecutive hot days). Temperatures are expected to gradually decrease after September.


Ø Influencing Factors

1.      El Niño Southern Oscillation (ENSO)


Recent observations: The 2020-2021 La Niña event has ended. Sea Surface Temperatures (SSTs) in the eastern Pacific have recently anomalously warmed to cold Neutral ENSO conditions.


Model forecast and guidance: Most models predict a continuation of ENSO-neutral throughout the first half of the wet season (June to August). A return to La Niña conditions though highly uncertain currently, is possible during the second half of the wet season (September to November) (50-55% confidence).


Expected impacts on rainfall and temperatures: ENSO neutral conditions tend to increase the level of uncertainty in the seasonal forecasts. Heat during the Caribbean Heat Season post a La Niña event tends to be reduced. If La Niña re-emerges, the region can expect to be at least as wet or even wetter than usual, with the potential for a busy peak of the Atlantic Hurricane Season.




2.      Climate conditions in the Tropical North Atlantic (TNA) and Caribbean Sea


Recent observations: SSTs have anomalously cooled to just below average in much of the Caribbean Sea and the Tropical North Atlantic (TNA) and around 0.5°C above average in the sub-tropical North Atlantic.

Expected conditions: Uncertainties exist in the forecast of the SSTs across the Caribbean Sea and the TNA through June to August 2021.

Expected impacts: Though SSTs have cooled slightly in and around the Caribbean, they remain warm enough and could contribute to above-average humidity, seasonal rainfall totals and reduced dry spell frequency.


 See table below with Climatological Normal/ Averages



June-July-August Season






474.2 to 756.8mm

544.4 to 768.5mm

Wet Days Normal

50 to 67 days

53 to 69 days

7-Day Dry Spells Normal


0 to 1


Average Maximum

32.2°C to 32.5°C

30.7°C to 31.2°C

Average Mean

28.2°C to 28.5°C

27.7°C to 28.1°C

Average Minimum

24.1°C to 24.6°C

24.7°C to 25.1°C