Well, I would like to state that this is NOT the case, at least not in the capital Bogotá and many other regions. Yes, most of the country is in warm climate, there are places where temperatures don't drop below 30 degrees Celsius, there are plenty of hot and humid cities with beaches and palm trees along the Pacific and Caribbean coasts of Colombia (which is, by the way, the only country in South America with access to these two seas), and there is no winter with snow and freezing temperatures.
Basically, what influences the temperatures, humidity and precipitation is the altitude, which can range from sea level up to 5775 meters. There are no seasonal variations and the weather stays the same pretty much all year round, wherever you are. Climate zones include deserts, tropical rain forest, savanna, and eternal glaciers, to mention but a few of the varieties. There are two rainy seasons during the year, called "invierno" or winter, around April and October.
Taking Bogotá as an example: the average temperature is a mere 15 degree Celsius, and can vary from 10 degrees at night to just above 20 degrees on very nice days, somehow comparable to September/October in France or Germany. Meaning you dress the same all year round, wearing long pants, long sleeves, and/or a light jacket every day. While they do get to wear warm sweaters, coats and even scarfs on cold days, Bogotanos never ever wear shorts or flip flops on warm days - only tourists do...!
There is no heating in Colombian houses in "tierra fría" (cold climate zone), which makes cold days appear even colder, more humid and quite uncomfortable. When I moved here four months ago, the rainy season happened to start and lasted for literally five or six weeks, making most days look something like this:
On very nice days, Bogotá looks more like this:
