It's equatorial! It's a bright sunny day, then suddenly a thunderstorm blasts you for a half hour. Then it's sunny again. Nobody bothers to carry umbrellas or raincoats. They just wait the rain out or ignore it and get wet.
Here you can see the rain coming down off in the distance on the other side of the river (in Colombia). We were lucky like that. The rain seemed to prefer to fall in Colombia. At least for the few days I was there!