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Tropical Waves, ITCZ Forecast To Bring Scattered Rainfall To T&T

June 18, 2025
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Tropical Wave 06 is forecast to bring rainfall to Trinidad and Tobago on Wednesday, with the Intertropical Convergence Zone expected to linger across our area over the next few days. Tropical Wave 07 is forecast to move across the region on Sunday. All three features will keep isolated to scattered rainfall on tap over the next five days, but strong wind shear, Saharan Dust, and moderate to strong low-level winds will limit widespread, persisting rainfall. As a result, gusty winds and street or flash flooding are likely in heavy showers, but riverine flooding is not expected.

What you need to know

— Rainfall: Over the next five days, through Sunday night, overall rainfall accumulations across Tobago are forecast to range between 40 and 60 millimeters. Across Trinidad, rainfall totals are forecast to range between 50 and 125 millimeters, with higher totals expected in the southern and eastern halves of the island, as well as in isolated areas of western coastal Trinidad.
— Saharan Dust: Mild to moderate dust will remain present through the next five days. Higher dust levels are likely to be present across Tobago compared to Trinidad.
— Hazards: The main hazards over the next five days will be gusty winds exceeding 50 km/h, as well as the threat of localized, short-lived street or flash flooding, both of which are likely to occur mainly in association with heavy showers and thunderstorms. Increased low-level winds, combined with gusts in heavy showers and thunderstorms, may cause weaker and/or larger trees to fall.
— Marine: Moderate seas are forecast in Trinidad and Tobago’s open waters, while choppy conditions are forecast in sheltered areas. All marine interests are advised to exercise caution in the vicinity of heavy showers and thunderstorms.

Latest Alert

There are no alerts, watches, or warnings in effect for Trinidad and Tobago from the Trinidad and Tobago Meteorological Service at this time.

Trinidad and Tobago is NOT under any tropical storm or hurricane threat, watch, or warning at this time.

The Forecast

Wednesday

Wednesday
5 10 0 1
Variably cloudy, particularly across Trinidad, slightly hazy, breezy, with isolated to scattered showers favoring Trinidad. There is a medium chance of isolated heavy showers and thunderstorms during the early morning and late morning through mid-afternoon periods, favoring Trinidad. A mostly settled evening, with isolated showers possible nearing midnight, favoring eastern areas of both islands.
Variably cloudy, particularly across Trinidad, slightly hazy, breezy, with isolated to scattered showers favoring Trinidad. There is a medium chance of isolated heavy showers and thunderstorms during the early morning and late morning through mid-afternoon periods, favoring Trinidad. A mostly settled evening, with isolated showers possible nearing midnight, favoring eastern areas of both islands.
5/10
Thunderstorm Chances
Medium

Thursday

Thursday
5 10 0 1
Scattered early morning showers, with a medium chance of heavy showers and thunderstorms, favoring eastern Trinidad and Tobago. Conditions give way to a partly cloudy, breezy/windy, and slightly hazy day. Isolated to scattered showers, with a medium chance of isolated heavy showers and thunderstorms return by late morning, favoring Trinidad, and continue through the mid-afternoon. Isolated showers, with the odd thunderstorm, continue into the night, favoring eastern areas initially.
Scattered early morning showers, with a medium chance of heavy showers and thunderstorms, favoring eastern Trinidad and Tobago. Conditions give way to a partly cloudy, breezy/windy, and slightly hazy day. Isolated to scattered showers, with a medium chance of isolated heavy showers and thunderstorms return by late morning, favoring Trinidad, and continue through the mid-afternoon. Isolated showers, with the odd thunderstorm, continue into the night, favoring eastern areas initially.
5/10
Thunderstorm Chances
Medium

Friday

Friday
5 10 0 1
Across Tobago, early morning isolated showers, with the low chance of a thunderstorm, gives way to a breezy, hazy and partly cloudy day, with the odd shower during the late morning through the afternoon. Across Trinidad, variably cloudy, breezy/windy, and hazy conditions interrupted by scattered showers from the early morning, with the medium chance of isolated heavy showers and thunderstorms favoring southern Trinidad during the early morning through the early afternoon. A mostly settled, breezy, and hazy evening and night, with isolated showers favoring eastern areas.
Across Tobago, early morning isolated showers, with the low chance of a thunderstorm, gives way to a breezy, hazy and partly cloudy day, with the odd shower during the late morning through the afternoon. Across Trinidad, variably cloudy, breezy/windy, and hazy conditions interrupted by scattered showers from the early morning, with the medium chance of isolated heavy showers and thunderstorms favoring southern Trinidad during the early morning through the early afternoon. A mostly settled, breezy, and hazy evening and night, with isolated showers favoring eastern areas.
5/10
Thunderstorm Chances
Medium

Saturday

Saturday
3 10 0 1
Mostly sunny, breezy/windy and slightly hazy with a few isolated showers, mainly across southern and eastern areas of Trinidad. Gusty winds are likely in rainfall activity. Nearing midnight, isolated heavy showers or thunderstorms (low chance) are possible, favoring southern Trinidad.
Mostly sunny, breezy/windy and slightly hazy with a few isolated showers, mainly across southern and eastern areas of Trinidad. Gusty winds are likely in rainfall activity. Nearing midnight, isolated heavy showers or thunderstorms (low chance) are possible, favoring southern Trinidad.
3/10
Thunderstorm Chances
Low

Sunday

Sunday
5 10 0 1
Partly to mostly cloudy, breezy/windy with isolated to scattered showers favoring Trinidad. There is a medium chance of isolated heavy showers and thunderstorms across Trinidad, during the early to mid-morning and early afternoon. Gusty winds are likely in rainfall activity.
Partly to mostly cloudy, breezy/windy with isolated to scattered showers favoring Trinidad. There is a medium chance of isolated heavy showers and thunderstorms across Trinidad, during the early to mid-morning and early afternoon. Gusty winds are likely in rainfall activity.
5/10
Thunderstorm Chances
Medium

Marine Forecast

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Seas Forecast To Be Agitated Into Weekend Once More

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June 18, 2025

Temperatures

Wednesday

Low: 25-26°C

High: 30-31°C

Thursday

Low: 24-26°C

High: 30-31°C

Friday

Low: 24-27°C

High: 29-31°C

Saturday

Low: 24-27°C

High: 31-32°C

Sunday

Low: 24-27°C

High: 31-32°C

Forecast Impacts

Flooding

Over the next five days, through Sunday night, overall rainfall accumulations across Tobago are forecast to range between 40 and 60 millimeters. Across Trinidad, rainfall totals are forecast to range between 50 and 125 millimeters, with higher totals expected in the southern and eastern halves of the island, as well as in isolated areas of western coastal Trinidad.

Street & Flash Flooding

Street & Flash Flooding
5 10 0 1
While daily rainfall accumulations may reach or exceed 25 millimeters in some areas, persistent rainfall is forecast to be limited by Saharan Dust and strong low-level winds, leading to fast-moving showers. Heavy showers and thunderstorms are still forecast, which may result in localized and short-lived street/flash flooding.
While daily rainfall accumulations may reach or exceed 25 millimeters in some areas, persistent rainfall is forecast to be limited by Saharan Dust and strong low-level winds, leading to fast-moving showers. Heavy showers and thunderstorms are still forecast, which may result in localized and short-lived street/flash flooding.
5/10
Likelihood
Medium

Riverine Flooding

Riverine Flooding
2 10 0 1
Daily rainfall accumulations over the next five days are forecast to generally remain below 25 millimeters, which limits the flood threat to street/flash flooding. While river levels may increase, concerns for riverine flooding across all river basins are low to very low at this time.
Daily rainfall accumulations over the next five days are forecast to generally remain below 25 millimeters, which limits the flood threat to street/flash flooding. While river levels may increase, concerns for riverine flooding across all river basins are low to very low at this time.
2/10
Likelihood
Very Low – Low

Forecast Rainfall Totals

  • Wednesday (Tropical Wave 06): Between 5 and 15 millimeters of rainfall across T&T, with higher totals favoring eastern coastal areas of both islands, western coastal, and the hilly regions of Trinidad exceeding 25 millimeters.
  • Thursday: Across Tobago, between 5 and 15 millimeters of rain is forecast, with isolated totals of up to 25 millimeters. Across Trinidad, between 15 and 25 millimeters of rainfall is forecast, with higher totals in the eastern and southern halves of the island, where localized amounts could exceed 25 millimeters.
  • Friday: Across Tobago, less than 5 millimeters of rain is forecast, with isolated higher totals. Across Trinidad, between 15 and 25 millimeters of rainfall is forecast, with higher totals in the eastern and southern halves of the island, where localized amounts could exceed 25 millimeters.
  • Saturday: Across Tobago and the northern half of Trinidad, little to no significant rainfall accumulation is forecast, with isolated totals up to 10 millimeters. Across eastern coastal and southern areas of Trinidad, between 5 and 15 millimeters of rainfall is forecast, with isolated totals up to 25 millimeters. Please note that there is higher-than-usual uncertainty regarding rainfall accumulations on Saturday.
  • Sunday (Tropical Wave 07): Between 10 and 25 millimeters of rainfall across T&T, with higher totals favoring Trinidad. Isolated totals exceeding 25 millimeters are possible, favoring eastern Trinidad.

Understanding Rainfall Accumulations

Putting the rainfall forecast into context, rainfall rates in excess of 50 millimeters per hour or areas that receive in excess of 25 millimeters within an hour tend to trigger street flooding across the country or flash flooding in northern Trinidad. For riverine flooding to occur, a large area of the country (not just in highly localized areas of western coastal Trinidad) would have to record upwards of 75 millimeters within 24 hours, and rainfall would have to fall across major rivers’ catchment areas.

Strong Thunderstorms

Strong Thunderstorms
2 10 0 1
While strong thunderstorms are not expected, locally heavy to violent rainfall rates are possible.
While strong thunderstorms are not expected, locally heavy to violent rainfall rates are possible.
2/10
Likelihood
Very Low – Low
What is a strong or severe thunderstorm?

Given how rare these types of thunderstorms are in our region – we classify a severe or strong thunderstorm as one that produces any of the following:

  • Damaging wind gusts exceeding 63 KM/H;
  • Frequent lightning (more than 30 cloud-to-ground strikes within a 10-minute period);
  • Hail (of any size);
  • Rainfall of more than 50 millimeters or more within an hour or exceeding 75 millimeters or more within three hours;
  • The sighting of a funnel cloud or touchdown of a waterspout/tornado associated with the thunderstorm.

Gusty Winds

Gusty Winds
7 10 0 1
Moderate to strong low-level winds are forecast. There is a high chance of gusty winds exceeding 50 KM/H particularly from Friday, mainly ahead of and during showers and thunderstorms. Sustained winds are likely to reach 35 KM/H during this period.
Moderate to strong low-level winds are forecast. There is a high chance of gusty winds exceeding 50 KM/H particularly from Friday, mainly ahead of and during showers and thunderstorms. Sustained winds are likely to reach 35 KM/H during this period.
7/10
Likelihood
High

With wind gusts exceeding 50 KM/H, whole trees can be in motion, with larger trees and weaker branches falling. Light outdoor objects can topple or become airborne, such as garbage cans, loose galvanize, construction material, and outdoor furniture. Tents may also jump.

Other Hazards

Mild to moderate levels of Saharan Dust are forecast across Trinidad over the next five days, with generally higher concentrations favoring Tobago and the remainder of the Windward Islands.

Saharan Dust Forecast

Why I May Not/Will Not See Rainfall?

A frequent complaint is that the forecast is wrong because I didn’t experience any rainfall. Scattered showers mean that you, individually, may experience some showers intermittently throughout the day, and there is a higher chance for this activity than for isolated activity. Widespread showers mean that nearly all people and areas can expect rainfall.

Through the forecast period, isolated to scattered rainfall is forecast.

Forecast Discussion

Tropical waves typically have fair weather ahead of the wave axis, though other features in the area such as surface troughs, increased atmospheric moisture, and local climatic effects, to name a few, may trigger showers and the odd thunderstorm. Following the passage of the wave, much of the active weather typically associated with a tropical wave occurs.
Tropical waves typically have fair weather ahead of the wave axis, though other features in the area such as surface troughs, increased atmospheric moisture, and local climatic effects, to name a few, may trigger showers and the odd thunderstorm. Following the passage of the wave, much of the active weather typically associated with a tropical wave occurs.

Tropical Waves (As of 2 PM June 9th)

— Tropical Wave 06: Located along 57W from 14N, moving west around 5-10 knots (18 km/h) with scattered showers. This wave is approximately 580 km east of T&T on Wednesday morning, forecast to move across T&T later today.
— Tropical Wave 07: Located along 43W from 12N southward, moving west at around 5-10 knots (18 to 28 km/h) with no significant cloudiness, showers, or thunderstorms. This wave is forecast to move across T&T on Sunday into Monday, dragging the ITCZ northward ahead of its passage, and a significant surge of Saharan Dust will follow.
— Tropical Wave 08: Located along 24W from 14N southward, moving west at 5-10 knots (18 km/h). This wave is still over 4,000 kilometers east of Trinidad and Tobago.

A weak tropical wave (Tropical Wave 06) is expected to move across T&T on Wednesday. Following this, on Thursday, the Intertropical Convergence Zone is projected to move northward, accompanied by a low-level trough, bringing increased surface convergence and instability mainly across Trinidad. By Friday and into the first half of Saturday, a ridge pattern will return, resulting in drier low and mid-level conditions that will limit rainfall. However, by Sunday, Tropical Wave 07 will arrive, pushing the Intertropical Convergence Zone northward again, leading to further surface convergence and instability.

However, over the next five days, Saharan Dust (and consequently, low relative humidities at low and mid-levels of the atmosphere), along with moderate to strong westerly wind shear and strong low-level winds, are expected to restrict persistent rainfall and the formation of strong thunderstorms or extreme rainfall rates.

Fortunately, the next five days of isolated to scattered showers and possible thunderstorms do not resemble last week’s pattern, which resulted in the Caroni River overflowing. In fact, the main hazards through early next week will be localized street and flash flooding, along with gusty winds exceeding 50 km/h in heavy showers or brief thunderstorms.

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