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Forecast: Tropical Waves To Move Across Area

July 23, 2025
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Well-defined tropical waves are rolling off the African Coast, with the first forecasted to move across the Lesser Antilles today (Wednesday), bringing anomalous wind flow, periods of cloudy skies, and scattered showers and thunderstorms to Trinidad and Tobago (T&T) and the Windward Islands. Unsettled weather is forecast through the next seven days as two more tropical waves move across the region, with low-level troughs and the Intertropical Convergence Zone also affecting the area.

What you need to know

— Rainfall: Over the next five days, through Sunday night, overall rainfall accumulations across Trinidad are forecast to range between 25 and 75 millimeters, with isolated totals up to 150 millimeters where slow-moving thunderstorms and heavy showers occur, particularly across western coastal areas. Across Tobago, between 25 and 50 millimeters of rainfall is forecast, with isolated higher totals possible along windward and eastern coastlines.
— Saharan Dust: A moderate surge of Saharan Dust will move across T&T from early Thursday (July 24th) with higher concentrations of dust across the northern half of the island chain. Concentrations are expected to decrease by Saturday morning (26th), and another short-lived but mild surge is forecast between Sunday morning (27th) and Monday night (28th).
— Hazards: Through the next five to seven days, heavy showers or thunderstorms are likely to lead to street or flash flooding, with gusty winds possible. With repeated afternoon showers and thunderstorms likely across northern and western areas, landslides are possible in elevated areas, particularly across northern and northwestern Trinidad. With light (and veering) winds through the atmosphere on Wednesday, Saturday, and Monday, funnel clouds are possible, favoring western and southern areas of Trinidad and Tobago. In isolated strong thunderstorms, frequent lightning is likely, favoring western Trinidad.
— Marine: Slight to moderate seas are forecast in Trinidad and Tobago’s open waters, while near-calm conditions are forecast in sheltered areas through Wednesday, with waves below one meter from Thursday. All marine interests are advised to exercise caution in the vicinity of heavy showers and thunderstorms. Spring Tides end on Sunday, July 13th.

Latest Alerts

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

The Forecast

Wednesday

Wednesday
7 10 0 1
A few early morning showers and isolated thunderstorms, favoring southwestern and eastern areas of Trinidad and across Tobago, are forecast to gradually diminish throughout the mid-morning, resulting in hot and partly cloudy conditions. By the late morning through the afternoon, isolated heavy showers and thunderstorms are possible once more, initially favoring the western half of Trinidad and along the East-West Corridor, spreading across both islands. An isolated strong thunderstorm or two may be possible, favoring northwestern Trinidad (afternoon) and northeastern Tobago (morning). Conditions are expected to settle by the evening, becoming increasingly breezy into the night. An odd shower or brief thunderstorm is possible, favoring southwestern Trinidad nearing midnight.
A few early morning showers and isolated thunderstorms, favoring southwestern and eastern areas of Trinidad and across Tobago, are forecast to gradually diminish throughout the mid-morning, resulting in hot and partly cloudy conditions. By the late morning through the afternoon, isolated heavy showers and thunderstorms are possible once more, initially favoring the western half of Trinidad and along the East-West Corridor, spreading across both islands. An isolated strong thunderstorm or two may be possible, favoring northwestern Trinidad (afternoon) and northeastern Tobago (morning). Conditions are expected to settle by the evening, becoming increasingly breezy into the night. An odd shower or brief thunderstorm is possible, favoring southwestern Trinidad nearing midnight.
7/10
Thunderstorm Chances
High

Thursday

Thursday
5 10 0 1
Early morning showers, periods of rain, and isolated to scattered thunderstorms are likely, initially across Tobago, northern and eastern Trinidad, gradually diminishing by the mid-afternoon. A hazy, partly cloudy and breezy afternoon and evening is forecast, with the odd shower or two favoring eastern areas of both islands.
Early morning showers, periods of rain, and isolated to scattered thunderstorms are likely, initially across Tobago, northern and eastern Trinidad, gradually diminishing by the mid-afternoon. A hazy, partly cloudy and breezy afternoon and evening is forecast, with the odd shower or two favoring eastern areas of both islands.
5/10
Thunderstorm Chances (AM)
Medium

Friday

Friday
5 10 0 1
A few early morning showers, favoring southern and eastern areas of both islands, are forecast to give way to a mostly hot and sunny start to the day. By the late morning, increased cloudiness is forecast to develop across Trinidad, with isolated to scattered showers developing across the country, and isolated heavy showers and thunderstorms favoring southern and western areas of Trinidad. A mostly settled evening and night for Trinidad, with isolated showers likely across Tobago through the night.
A few early morning showers, favoring southern and eastern areas of both islands, are forecast to give way to a mostly hot and sunny start to the day. By the late morning, increased cloudiness is forecast to develop across Trinidad, with isolated to scattered showers developing across the country, and isolated heavy showers and thunderstorms favoring southern and western areas of Trinidad. A mostly settled evening and night for Trinidad, with isolated showers likely across Tobago through the night.
5/10
Thunderstorm Chances
Medium

Saturday

Saturday
6 10 0 1
Pre-dawn showers and isolated thunderstorms, generally favoring offshore and southern/eastern coastal areas, are forecast to give way to a mostly hot, sunny and slightly hazy day. By the late morning through the afternoon, isolated to scattered showers and thunderstorms are forecast to develop, favoring but not limited to southern and western halves of Trinidad and western Tobago. Conditions to settle by the late afternoon into the evening for both islands.
Pre-dawn showers and isolated thunderstorms, generally favoring offshore and southern/eastern coastal areas, are forecast to give way to a mostly hot, sunny and slightly hazy day. By the late morning through the afternoon, isolated to scattered showers and thunderstorms are forecast to develop, favoring but not limited to southern and western halves of Trinidad and western Tobago. Conditions to settle by the late afternoon into the evening for both islands.
6/10
Thunderstorm Chances
Medium – High

Sunday

Sunday
3 10 0 1
Pre-dawn showers and isolated thunderstorms, generally favoring offshore and eastern coastal Trinidad and southern coastal Tobago, are forecast to give way to a mostly hot, sunny and slightly hazy day. By the late morning through the afternoon, isolated to scattered showers and the odd thunderstorm are forecast to develop, favoring but not limited to western half of Trinidad. Conditions to settle by the late afternoon into the evening for both islands.
Pre-dawn showers and isolated thunderstorms, generally favoring offshore and eastern coastal Trinidad and southern coastal Tobago, are forecast to give way to a mostly hot, sunny and slightly hazy day. By the late morning through the afternoon, isolated to scattered showers and the odd thunderstorm are forecast to develop, favoring but not limited to western half of Trinidad. Conditions to settle by the late afternoon into the evening for both islands.
3/10
Thunderstorm Chances
Low

Looking further ahead, on Monday through Tuesday, another well-defined tropical wave is forecast to move across the region, bringing more showers and thunderstorms to T&T and the Lesser Antilles.

Marine Forecast

Temperatures

Wednesday

Low: 24-25°C

High: 31-33°C

Feels Like: 35-42°C

Thursday

Low: 24-25°C

High: 29-31°C

Feels Like: 32-37°C

Friday

Low: 25-27°C

High: 31-34°C

Feels Like: 35-48°C

Saturday

Low: 25-27°C

High: 31-34°C

Feels Like: 35-48°C

Sunday

Low: 25-27°C

High: 32-34°C

Feels Like: 35-48°C

Forecast Impacts

Flooding

Over the next five days, through Sunday night, overall rainfall accumulations across Trinidad are forecast to range between 25 and 75 millimeters, with isolated totals up to 150 millimeters where slow-moving thunderstorms and heavy showers occur, particularly across western coastal areas. Across Tobago, between 25 and 50 millimeters of rainfall is forecast, with isolated higher totals possible along windward and eastern coastlines.

Street & Flash Flooding

Street & Flash Flooding
7 10 0 1
Daily through Saturday, isolated heavy showers and thunderstorms are forecast, particularly across northern and western Trinidad which has high vulnerability to street/flash flooding. As a result, the likelihood of flash flooding is high, mainly on Wednesday through Saturday.
Daily through Saturday, isolated heavy showers and thunderstorms are forecast, particularly across northern and western Trinidad which has high vulnerability to street/flash flooding. As a result, the likelihood of flash flooding is high, mainly on Wednesday through Saturday.
7/10
Likelihood
High

Riverine Flooding

Riverine Flooding
3 10 0 1
Though chances are low at this time, with the potential for 75 millimeters of rainfall falling across parts of Trinidad within a 24 to 48-hour period, major river levels are likely to rise and remain contained. However, smaller tributaries, particularly with repeat rainfall over the same areas, may become overwhelmed if the most extreme scenarios occur. At this time, if you live in a flood-prone area, pay close attention to watercourses in your area.
Though chances are low at this time, with the potential for 75 millimeters of rainfall falling across parts of Trinidad within a 24 to 48-hour period, major river levels are likely to rise and remain contained. However, smaller tributaries, particularly with repeat rainfall over the same areas, may become overwhelmed if the most extreme scenarios occur. At this time, if you live in a flood-prone area, pay close attention to watercourses in your area.
3/10
Likelihood
Low

Forecast Rainfall Totals

  • Wednesday: Most areas will see rainfall ranging from 5 to 10 millimeters, with isolated totals between 10 and 25 millimeters across both islands. The rainfall is expected to favor western coastal, southern, and eastern coastal Trinidad, as well as north and east Tobago. With the possibility of locally strong thunderstorms on Wednesday, even higher 24-hour totals are possible, favoring northwestern Trinidad.
  • Thursday: Across Tobago, between 5 and 15 millimeters of rain are possible, with higher totals favoring the southern and eastern coasts. Across Trinidad, between 10 and 25 millimeters of rainfall is forecast, with isolated totals between 25 and 50 millimeters favoring the western half of Trinidad.
  • Friday: Across Trinidad and Tobago, between 5 and 15 millimeters of rainfall is possible, with isolated totals between 15 and 35 millimeters favoring southern and western areas of Trinidad. [Low confidence]
  • Saturday: Between 5 and 15 millimeters of rainfall across Trinidad and Tobago, with totals up to 35 millimeters favoring western Trinidad. [Low confidence]
  • Sunday: Less than 5 millimeters across both islands, with isolated totals between 5 and 15 millimeters favoring eastern and western coastal areas of 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
6 10 0 1
There is a medium to high chance of strong thunderstorms on Wednesday, with a low to medium chance of strong thunderstorms on Saturday and on Monday. The main hazards with these strong thunderstorms will be funnel clouds, frequent lightning, and violent rainfall rates.
There is a medium to high chance of strong thunderstorms on Wednesday, with a low to medium chance of strong thunderstorms on Saturday and on Monday. The main hazards with these strong thunderstorms will be funnel clouds, frequent lightning, and violent rainfall rates.
6/10
Likelihood
Medium – High
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
4 10 0 1
Over the next five days, overal wind speeds are forecast to be light to moderate, with sustained winds below 25 km/h and gusts below 45 km/h. However, in strong thunderstorm activity, wind gusts in excess of 55 km/h are possible.
Over the next five days, overal wind speeds are forecast to be light to moderate, with sustained winds below 25 km/h and gusts below 45 km/h. However, in strong thunderstorm activity, wind gusts in excess of 55 km/h are possible.
4/10
Likelihood
Low – Medium

With wind gusts exceeding 55 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

Moderate concentrations of Saharan Dust are forecast from Thursday. Hot temperatures are also forecast this week, particularly on Friday through Sunday, with heat indices reaching levels that warrant caution.

Saharan Dust Forecast

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Short-lived Saharan Dust Surge Forecast on Thursday

Over the next seven days, Saharan Dust surges are forecast to trail tropical waves, with the first, short-lived surge forecast to move across T&T from early Thursday, trailing Tropical…
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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.

Isolated to scattered rainfall is forecast on Wednesday through Saturday, with isolated rainfall possible on Sunday.

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 2:00 AM July 8th)

— Tropical Wave 18 (formerly Invest 94L): Located along 57W, moving west around 10-15 knots (18-28 km/h). This large and well-defined tropical wave is forecast to move across the Lesser Antilles today, bringing the ITCZ across the Windward Islands. An upper-level trough will also enhance shower and thunderstorm activity, mainly north of T&T. The ITCZ and a trailing low-level trough will affect T&T on Thursday following this wave.
— Tropical Wave 19: Located along 41W from 18N southward, moving west at around 10 knots (18 km/h), forecast to move across T&T late Friday into Saturday.
— Tropical Wave 20: Another large and well-defined tropical wave located along 23W with a 1013 mb low-pressure system located along the wave axis. This wave is forecast to move across the Windward Islands on Monday.

On Wednesday, a large and well-defined tropical wave (TW18) is forecast to move across the Lesser Antilles, with the heaviest rainfall and stronger winds forecast to move across the central and northern portion of the island chain. For Barbados and Grenada, through Guadeloupe, between 25 and 75 millimeters of rainfall are possible with this tropical wave between Wednesday and Thursday, with locally higher totals on windward coastlines. Wind gusts, mainly between 55 km/h and 85 km/h, are possible for Dominica northward to Guadeloupe, particularly across elevated terrain and in thunderstorms. The worst of the weather associated with this tropical wave is forecast to remain north of Trinidad and Tobago.

However, this wave is forecast to bring the ITCZ across T&T and influence the wind field across the lower half of the atmosphere across Trinidad and Tobago. As a result, light to moderate southerly to southeasterly winds are forecast to prevail across T&T on Wednesday, with wind speeds decreasing from late morning through the afternoon. As a result, slow-moving showers and thunderstorms are likely across T&T, particularly those that form from sea-breeze convergence and daytime heating along western T&T, and along the south-facing slopes of the Northern Range and Main Ridge. Any activity that develops will be steered northwestward, resulting in convergence along the mountain range, enhancing existing activity. Additionally, with veering winds through the lower atmosphere, minimal wind shear, a saturated atmosphere, and ample instability, locally strong thunderstorms are possible with efficient rainfall production likely. The result will be heavy rainfall in slow-moving showers and thunderstorms, with an elevated flood risk on Wednesday. This wind profile is also supportive of funnel cloud development along southern and western Trinidad on Wednesday (and to a lesser extent on Saturday).

By Thursday into Friday, a low-level trough trailing Tropical Wave 18 moves across T&T under very similar atmospheric conditions. However, low-level winds are forecast to increase as well as wind shear, leading to less ideal conditions compared to Wednesday. Still, heavy rainfall is likely, as the atmosphere remains primed for efficient rainfall production, with precipitable water levels above 2-2.25 inches (50+ mm). While widespread rainfall is not currently forecast, isolated to scattered early morning and late-morning through afternoon showers and thunderstorms will pose a street/flash flood threat.

On Saturday, Tropical Wave 19 moves across the region with very similar atmospheric conditions: low to moderate wind shear, a saturated atmosphere, ample vertical instability, marginally favorable upper-level conditions, and light to moderate veering winds through the atmosphere. As a result, more showers and thunderstorms remain forecast for Saturday.

By Sunday, a surge of Saharan Dust significantly dries out the atmosphere, reducing rainfall chances across T&T and the southern Windwards. Still, this dry airmass across T&T will be short-lived as Tropical Wave 20 moves in on Monday through Tuesday, bringing with it the ITCZ northward.

While there are no alerts, watches, or warnings in effect for T&T from the Trinidad and Tobago Meteorological Service at this time, many of the islands across the Lesser Antilles that are forecast to see more impactful weather, are under flood advisories or general yellow-level alerts for flooding, wind gusts, and landslides due to Tropical Wave 18.

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