Interesting Map. Fairly suprising that there are no WT cyclists from Nariño, Valle de Cauca or Santander this year.
Seriously, though. If you are an aspiring pro would you continue to train in the coldest, wettest part of your land? Typical of coastal tropical climates, should you be smart enough to train near those warm waters; is that it rains late in the day. There are also rain shadows where it's dryer. General comparisons to tropical mega zones to coastal Belgium is only relevant when you hunt for cold rain, good beer and chocolate.
We trained in Malibu a few years back in early Spring. Not a shock to see Geraint and a teammate climbing hills there instead of where they came from. It rains and is cold in both places each morning. One gets warmer as the day goes on...
I mean, I guess my main earlier point was that there is really no escaping the rain in Colombia. It is, if you believe the rankings, the wettest country in the world -full stop-. As the above map shows, the cycling heartland is closer to the mountains (as with most places, I guess). Where it does usually, but far from always, rain late in the day. Also, mechanics's time is pretty cheap and they are plentyful, the bikes and components are free if you're in the WT, so most pros seem to ride outside often and take advantage of the ample mountain roads and the weather that is often bad, but hardly ever so bad that indoor training looks like a better alternative. And the pretty decent local race calendar, which is full of mountain climbs and descents, is also often hit by bad weather (and I doubt the bad weather protocol has ever been triggered).
Yes, as Squire said, this does not mean that all Colombians are good bad weather riders. But and I guess this would be my second and more applicable point, I would venture that, again, since there is pretty much no escape from the rain in Colombia, contra what some posters seem to assume, most Colombian WT pros are at least pretty used to riding in the rain and the cold.