Map from Google - Isla_Margarita

In Isla de Margarita, a few kilometres off the north coast of Venezuela, the climate is tropical, hot and humid all year round, with a dry season from late February to May, and a rainy season, felt more or less depending on area, from June to mid-February.
The maximum temperatures are almost always above 30 °C, and the minimum temperatures almost always above 20 °C; they are slightly lower from December to February, and higher in the two warmest periods, ie in April-May and in September-October, due to the passages of the sun at its zenith, when the temperature can reach 34/35 °C. The sun passes directly overhead at noon around April 20 and August 20, and remains close to the zenith in the summer months, so you need appropriate protection in the central hours of the day.
Here are the average temperatures.
Average temperatures - Isla Margarita
Isla MargaritaJanFebMarAprMayJunJulAugSepOctNovDec
Min (°C)212122232424232424242322
Max (°C)313132323232323333333231

The wind blows throughout the year, as northeast trade winds in winter, and southeast trade winds in summer, tempering the heat.
Precipitation is not abundant along the coasts and in low-lying areas, but there are important variations depending on area. Typically the eastern part of the island (called Paraguachoa) is rainier than the western one (called Macanao Peninsula), besides hilly areas are wetter than flat areas.
The rainy season, from June to mid-February, is actually divided into two: in the first part (June to October), there are long periods without rain, but thunderstorms can occasionally occur, sometimes intense; in the second part (November to mid-February) the rains are due to the northeast trade winds, and occur almost only in the eastern part of the island, and in particular along the coast facing north-east: in some years, in this second period there may be heavy rains and flooding.
The result is that in the flat areas to the west and the south (see Punta de Piedras or the airport area, and much of the Macanao Peninsula), which are drier, the rainy season goes from June to mid October, peaking from June to August, when the rains are just over 100 millimetres per month; the rains are rare even in this period, but when they occur, they may be abundant. At the Airport, only 625 millimetres of rain per year fall.
On the contrary, in the eastern side (see La Asunción, Parquito Playa, Playa el Agua), the summer rains are a bit scarcer, since they reach at most 75 mm in August, but then the rains become more abundant, from November to mid-February, when they swing from 95 to 130 mm per month. In La Asunción, 770 mm of rain per year fall, which is not so much, but for the brevity of the dry season (the only months when it rains very little are March, April and May), the landscape is green.
Here is the average precipitation in La Asunción (located in the east, therefore more exposed to the rains caused by the northeast trade winds).
Average precipitation - La Asunción
La AsunciónJanFebMarAprMayJunJulAugSepOctNovDecYear
Prec. (mm)10560352525507075505095130770

La Asunción

The greenest areas are the inland hills: the highest point is at 750 metres in the Macanao Peninsula (the only green part of the peninsula is in fact the inland hilly area), and 900 metres in Paraguachoa, where there is also a national park, the Parque Nacional Cerro El Copey. Hills and mountains in fact enhance the formation of rain.

The amount of sunshine in Isla Margarita is good all year round, as generally the good weather prevails.

The sea is warm enough for swimming all year round, as you can see in the following table.
Sea temperature - Isla Margarita
Isla MargaritaJanFebMarAprMayJunJulAugSepOctNovDec
Sea (°C)262626262727272828282827

Isla Margarita is located in the extreme southern limit of the trajectory of the hurricanes, which means that it is very rarely affected; however, the hurricane season runs from June to November, and the highest probability is between August and October. In September 2004, Hurricane Ivan, which devastated Grenada, brought moderate winds and storm surge on Isla Margarita and the Venezuelan coast, passing just north of the island. In August 1974, however, Isla Margarita was directly affected by Tropical Storm Alma, and in July 1933 it was hit by Hurricane 2 of that year.

Macanao Peninsula

The island, along with the two smaller islands Cubagua and Coche, is part of the island state of Nueva Esparta. The two smaller islands, flat and even closer to the mainland, are definitely arid.

When to go

The best time to go to Isla Margarita runs from late February to late May, being the driest, during which it almost never rains. Even during the rainy season, nice days actually prevail, but sometimes strong thunderstorms can break out. If you plan to visit the island from November to mid-February, you will prefer the western part (Macanao Peninsula), or the western part of Paraguachoa.