Due to Colombia’s position near the equator, it doesn’t enjoy seasons in the strictest sense of the word. Temperature variations in the country depend on location and altitude: the coast is always hot and humid; Bogotá is mostly drizzly, overcast, and chilly during the nights. The higher (or lower) you travel in terms of altitude determines the various climates you’ll experience. Wet and dry seasons exist in most areas of the country, with precipitation levels varying between locations.
An exception to this is the Amazon region of Colombia, which doesn't have a wet and dry season but rather seasons that denote the water levels of the Amazon River. During the low-water season (June until November), there are more opportunities for tours and great opportunities for spotting wildlife.
Crowds & Costs
The summer months north of the equator are certainly popular times for travelers to visit Colombia. You'll find that August, despite representing the end of this season, is still a busy month for Colombia, tourism-wise. That said, many hotels in the country view the peak season as comprising mostly June and July, so depending on when you arrive, you might just be able to take advantage of lower fares right when hotels lower their prices.
Where to Go
One of the great things about Colombia is that because there's such diversity of topography and climates, there are places that will appeal to any kind of traveler. If you want a bit of jungle and river adventure, you can visit Amazonas. As mentioned above, August falls within the Amazon's low-water season. Lower river levels mean there are more opportunities for wildlife spotting, there are more tours open, and lovely Amazonian villages like Puerto Nariño have more land area to enjoy.
For those looking for a refreshing alternative to the scorching summer months back home, consider visiting Medellín. Its perpetual springlike climate (its average highs fall into the 71-74°F range), means this city and its surrounding Antioquia Department are a refreshing alternative to the hotter locales. Plus there's a lot to do here, be it flying high over the city on its gondola cable car network, or making a day trip to Guatapé and hiking up the massive El Peñol rock.
Another reason to come to Medellín in August is that this is when the Feria de Flores occurs. More on this below.
What to Do
If you only visit one place and do one thing during your Colombian holiday in August, make sure it's Medellín and the Feria de Flores. This "Festival of the Flowers" is such an ingrained part of the Paisa (people from Medellín) culture, that it is akin to the New Years Ball Drop in Times Square or Carnival in Río de Janeiro.
That's because Medellín is the largest exporter of cut flowers in the world. Local flower farmers, known as silleteros, prepare all year for a celebration of this heritage by designing giant, elaborate floral displays. Then they take to the streets of downtown Medellín in a parade known as Desfile de los Silleteros. Back in 1957, when the festival first started, some 40 silleteros marched. These days you'll see hundreds parading down the streets in long processions, showing off their labor of love like giant strutting peacocks. More info below.
Feria de Flores. In the "City of the Eternal Spring," flowers are always in bloom. Medellín celebrates this every year during the first two weeks of August, when harvesters line the streets carrying great floral displays on their backs. There are also horse shows, concerts, and street parties.
Festival del Viento y de los Cometas. Whatever the windiest August weekend is in in Villa de Leyva, that’s when the town holds its famous kite festival. For three days everyone packs the central plaza to display their aerial prowess. Contests involve, among other things, best handmade kite and best practitioner in the kids’ division.
Traveling to Colombia in August? Check out these great itinerary ideas.
Cartagena, Flower Festival, and the Colombian Amazon. This unique 11-day itinerary hinges on an event which takes place in Medellín every August: the Batalla de Flores, or "Festival of the Flowers," is one of the biggest spectacles in the entire country. So set aside some time at the end of summer and prepare for an excursion that you won't soon forget.
Adventure in Colombia's Amazon Region. Hike to Maloka Macuna to experience of the indigenous way of life, sleep in a treehouse in the rainforest at Reserva Natural Tanimbuca, and take a peque-peque (motorized dugout canoe) and explore Lago Tarapoto and see the famous pink river dolphins.