St Vincent and the Grenadines Geography & Climate

St Vincent and the Grenadines covers about 389 square kilometres in the Windward Islands, of which the main island of St Vincent accounts for around 344.

St Vincent

Volcanic, steep and green, with a mountainous spine running its length and rainforest on the windward slopes. La Soufriere, at 1,234 metres, is an active stratovolcano at the northern end, and it is genuinely active: it killed around 1,600 people in 1902, erupted again in 1979, and in April 2021 produced explosive eruptions that covered the north of the island in ash and forced the evacuation of some 20,000 people. Beaches on this island are volcanic black and grey.

The Grenadines

A chain of some thirty islands and many more cays running south-west toward Grenada, which administers the southernmost few. They are lower, older and drier than the main island, ringed by coral and white sand. The inhabited ones are Bequia, Mustique, Canouan, Mayreau, Union Island and Palm Island.

Tobago Cays

Five uninhabited islets sheltered behind Horseshoe Reef, a two-kilometre arc of coral that takes the Atlantic swell and leaves flat, shallow, extraordinarily clear water inside. The whole area is a marine park.

A border drawn through a chain

The Grenadines are a single geological chain but not a single country: the line falls between Petit St Vincent and Petite Martinique, so the northern two-thirds belong here and the southern islands, Carriacou among them, are administered by Grenada. Yachts cross an international border mid-archipelago and must clear customs to do it, which is the one piece of paperwork that regularly catches out people sailing south.

Reef and seagrass

Extensive fringing reef through the chain, and the seagrass beds that support the green turtle population.

The country has a tropical maritime climate moderated by the north-east trade winds, with a sharp difference in rainfall between the mountainous main island and the low Grenadines.

Temperature

Steady through the year: daytime highs of 28 to 31°C and nights of 22 to 25°C, with the trades keeping it comfortable. There is no cool season.

The seasons

The dry season runs December to May and is reliably sunny and breezy. The wet season runs June to November, hotter and more humid, with heavy showers that usually pass quickly.

Two very different rainfalls

Mountainous St Vincent wrings moisture out of the trades and receives up to 3,800 millimetres a year on its interior heights, which is why it is rainforest. The Grenadines, low and flat, get around 1,000 millimetres and are dry scrub with white-sand beaches. This is why the small islands are the beach destination and the main island is the green one, and why the Grenadines depend on rain catchment and imported water.

Hurricanes

The season runs June to November, peaking August to October. The islands lie in the path; Hurricane Beryl caused severe damage in the southern Grenadines in July 2024, devastating Union Island and Mayreau.

Choosing between the two

The rainfall split is the practical planning point. If the trip is about beaches and water, the Grenadines deliver in almost any month; if it is about rainforest, waterfalls and the volcano, the main island is greener but wetter and its interior can be in cloud for days. Most itineraries that work give the main island two or three days and the chain the rest.

Volcanic ash

Not weather, but the 2021 eruption shows that ashfall can close the airport and affect air quality across the region for days.