Map from Google - Venezuela

In Venezuela the climate is hot all year round, at least at low altitudes, being located just north of the Equator. The main differences is found in the seasonal rain pattern: there is a dry season (which generally runs from mid-December to mid-April) and a rainy season (generally, from late April to mid-November). The rainy season is more sultry, therefore more unpleasant, while the dry season is usually the coolest, albeit slightly.
There are also mountain ranges and plateaus to take into account.

In the northern coasts, there are significant differences in rainfall: the eastern coast is quite rainy, so much so that the huge Orinoco delta is covered with mangroves and rainforests. Here, about 2,000 millimetres (79 inches) of rain per year fall, and there is not a real dry season, although the least rainy period is from February to March.
Proceeding west, precipitation goes down to around 1,000 mm (40 in) per year, or even below, as happens in Guiria, where it's about 900 mm (35.5 in), and the period from January to May is quite dry.
Further to the west, in Barcelona, only 650 mm (25.6 in) of rain per year fall, and the rainy season runs from June to September, while it rains very little from December to April.
Here is the average precipitation in Barcelona.
Average precipitation - Barcelona
Prec. (mm)104674510013511075655025632

Here are the mean temperatures of Barcelona.
Average temperatures - Barcelona
Min (°C)202021222322212121222120
Max (°C)313132333332313132323231
Min (°F)686870727372707070727068
Max (°F)888890919190888890909088

The islands of the Caribbean Sea (Isla Margarita, Los Roques, La Orchila, La Blanquilla, Los Hermanos, Los Testigos, La Tortuga) are arid, since the annual precipitation amount is usually around 500 mm (20 in), and sometimes even lower. Here the rainy season is not so noticeable, because in the summer months the prevailing winds, the southeast trade winds, blow from the mainland, and in fact the islands are part of the Leeward Antilles. But from November to mid-February, some additional showers may occur, due to the northeast trade winds which blow in this period.
The north-west coast bordering the Gulf of Venezuela (see Maracaibo, Coro), is usually sheltered from the northeast trade winds. In the short stretch of coast belonging to the Guajira Peninsula we find the Venezuelan side of the Guajira desert, where less than 300 millimetres (12 inches) of rain per year fall. North of Coro, and south of the isthmus connecting the mainland with the Paraguaná Peninsula, we find the national park of Medanos de Coro, where there is a small sandy desert, with towering dunes as high as 40 metres (130 feet).
In Maracaibo from December to April it almost never rains, and usually the rains are not abundant even in the period from May to October, excluding October, when 150 mm (6 in) of rain fall. However, the rains are irregular from year to year, and sometimes they can be plentiful, although there is a break in the rains in July which is almost always respected.
Here is the average precipitation.
Average precipitation - Maracaibo
Prec. (mm)2182070554555701508515576

From May to October, however, the temperatures are high, while January and February (and also the Christmas period) are the least hot (or better, the least sultry and therefore the most pleasant) and the sunniest.
Average temperatures - Maracaibo
Min (°C)232323242525252525242424
Max (°C)323233333334343434333333
Min (°F)737373757777777777757575
Max (°F)909091919193939393919191

Isla Margarita

For swimming, the Caribbean sea is warm all year round, as we can see from the water temperatures at Maracaibo.
Sea temperature - Maracaibo
Sea (°C)262526262727272828292827
Sea (°F)797779798181818282848281

The northernmost part of Venezuela, namely the Paraguanà Peninsula, the Paria Peninsula and the islands, is located in the southern end of the trajectory of hurricanes, which means that it can sometimes be affected by tropical cyclones, more or less intense. The season in which hurricanes form, runs from June to November, but the phenomenon is more likely between August and October. For example, these areas were affected by Hurricane 2 (or Trinidad hurricane) in July 1933, Tropical Storm Alma in August 1974, and were touched by Hurricane Ivan in September 2004, which passed to the north.

The capital Caracas is located in a valley, about 15 km (9 miles) away from the sea, but from which it is isolated by the mountain range called Cordillera de la Costa Central, in the part of the range where the Ávila National Park is found; moreover its altitude, about 900 metres (3,000 feet) is sufficient to temper the heat, making the climate pleasant throughout the year, so that the temperatures are around 24/27 °C during the day, and 13/17 °C at night. In fact, from this altitude the so-called tierras templadas (temperate lands) begin. The coolest period is from December to March, when at night the temperature can drop to 10 °C (50 °F). From May to December, the rains are quite frequent, however, they occur in the form of showers and thunderstorms, that soon leave space for the return of the sun. The period from January to mid-April is the driest, and sees very little rainfall. The total annual precipitation is about 830 mm (32.5 in).
Here is the average precipitation.
Average precipitation - Caracas
Prec. (mm)20101533801001101101051109545833

From December to February, in the cooler hours the fog may appear. Sometimes, especially from March to September, the down-slope wind coming from the ranges of El Ávila and Naiguatá, can lead to sudden increases in temperature, so that the air becomes torrid.
Average temperatures - Caracas
Min (°C)131314161717171616161614
Max (°C)242526262726262627262526
Min (°F)555557616363636161616157
Max (°F)757779798179797981797779

Other cities in Venezuela are located at high elevation as well, and therefore their climate is tempered by altitude. Barquisimeto is located at 600 metres (2,000 feet), so the temperature is a bit higher than in Caracas: around 28/29 °C (82/84 °F) during the day, and 20/21 °C (68/70 °F) at night. The city is located in the north-western arid region, in fact it receives only 540 mm (21.2 in) of rain per year, and they are quite irregular but most abundant from April to July.
Mérida is located instead at a higher altitude, 1,500 metres (5,000 feet), so it has a cooler climate, with average highs around 23/25 °C (73/77 °F).
Average temperatures - Mérida
Min (°C)151516171717161717161615
Max (°C)232324242424252525242423
Min (°F)595961636363616363616159
Max (°F)737375757575777777757573

The city is located in the south-west, in a valley a short distance from the highest mountain in Venezuela, Pico Bolìvar, towering with its 4,978 metres (16,332 feet). Here the rains are plentiful: 1,700 mm (67 in) per year, with a very rainy period from April to November, and a fairly dry period from January to March.
Here is the average precipitation.
Average precipitation - Mérida
Prec. (mm)405050170230160130140190260190801690

Mérida cable car
South of Caracas, there is a large flat area (called El Llano or Los llanos as plural), very interesting from the point of view of wildlife and covered by savanna (especially in the states of Apure and Guarico). From the point of view of the climate, it is characterized by a sharp alternation between a dry and a rainy season. In this area there are some national parks, such as Aguaro-Guariquito and Santos Luzardo. The city of San Fernando is located in this area. Lying in the lowlands, it is hot all year round, but due to the distance from the sea, during the dry season (which runs from mid-November to mid April), before the rainy season (ie March and April), the temperatures reach considerable values: 35/36 °C (95/97 °F) in March and April are the norm. But then the rains come, very intense from June to mid-September, and the temperature returns to tropical values, around 29/30 °C (84/86 °F), in addition to moisture, which becomes high.
Here is the average precipitation.
Average precipitation - San Fernando
San FernandoJanFebMarAprMayJunJulAugSepOctNovDecYear
Prec. (mm)14147018528030528017013040111490

Rainfall amounts to 1,500 mm (60 in) per year, but the dry season is too long to allow the forest to expand here. To visit this area, the best time is from December to January, which however is hot, because from February to April it's even hotter.
Average temperatures - San Fernando
San FernandoJanFebMarAprMayJunJulAugSepOctNovDec
Min (°C)222222232322222223222222
Max (°C)323336353231303031323232
Min (°F)727272737372727273727272
Max (°F)909197959088868688909090

To the east, the area of Ciudad Bolìvar and El Tigre (ie the southern part of the states of Anzoategui and Monagas, and the north of Bolìvar) has an even more arid landscape, since precipitation is lower than 1,000 mm (40 in) per year. The rainfall pattern is similar, however, with a rainy season from May to October.
Another area covered by the savanna, is located in the south-east, in the plateau called Gran Sabana on the border with Guyana and Brazil. This plateau is part of the larger Guiana Shield. In this area, there are also mountain peaks such as Mount Roraima and Kukenan Tepui. In Santa Elena, at 900 metres (3,000 feet) above sea level, the heat is less intense than in the plains, being tempered by altitude.
Here are the average temperatures.
Average temperatures - Santa Elena
Santa ElenaJanFebMarAprMayJunJulAugSepOctNovDec
Min (°C)161718181818171717171717
Max (°C)303131302928282829293029
Min (°F)616364646464636363636363
Max (°F)868888868482828284848684

In Santa Elena the rains are quite abundant, amounting to 1,600 millimetres (63 inches) per year. The driest months are January and February, while the wettest period is from May to August.
Here is the average precipitation.
Average precipitation - Santa Elena
Santa ElenaJanFebMarAprMayJunJulAugSepOctNovDecYear
Prec. (mm)50609513521525021517095901301201625

Further to the west, but always in the state of Bolìvar, we find the huge Canaima National Park, which is generally more humid and has greener landscapes; here we find incredible waterfalls like Salto Angel, 979 metres (3,211 feet) high, and Salto Kukenan, 674 metres (2,211 feet) high.

Salto Angel

In eastern and southern Venezuela, from the Orinoco delta to the southern state of Amazonas (with the exception of the aforementioned Gran Sabana), where the Venezuelan side of the Amazon is found, the climate is so rainy as to give life to rainforests. Rainfall exceeds 2,000 mm (79 in) per year, and the relatively dry season (in which, however, the rains are not so rare) is from December to March.

As we have already mentioned, in Venezuela the are also high mountains, especially in the west, where there is a small portion of the Andes (the Cordillera de Mérida). In the aforementioned Pico Bolìvar, at almost 5,000 metres (16,400 ft) above sea level, there are three small glaciers. This makes us understand that it is around 5,000 metres (16,400 ft) that one would expect an average temperature around freezing (as we have seen, since the country lies at the Equator, there is a quite constant temperature throughout the year). Usually, it gets cold above 3,000 metres (9,800 ft).

When to go

Apart from the individual regions, of which the climate was explained in detail, wanting to find the best time to visit all of Venezuela, you can choose January and February, also including the Christmas period at the end of December.
More generally, the dry period, or in any case the least rainy (mid-December to mid-April) is preferable to the rainy season (from late April to mid-November).

What to pack

For the plain, in general, light clothing all year round. For the forest, tropics-friendly, loose fitting clothing, light shirts and pants of natural fibres (cotton, linen) or synthetics that breathe, maybe with long sleeves for mosquitoes; a light sweater and a light raincoat for thunderstorms, or even for the savanna during the rainy season. For the coasts, although it's always hot, you can bring a light sweatshirt for the breeze, especially from December to February.
For Caracas, Mérida, and tierras templadas, light clothing, a sweater for the evening, a jacket for the evening especially from December to March; raincoat or umbrella from May to December in Caracas, and throughout the year in Mérida, but especially from April to November.
For the high mountains, warm clothes, down jacket, hat, gloves, scarf, hiking shoes.