I guess my question back to you is, would you change your plans? If the answer to that question is no, then I would not worry about. The reality is that you are going to the tropics and while this is the end of the drier season and according to weather on my i-phone it is sunny and 86 right now, it can change quickly. Pop up thunderstorms are known to occur on a regular basis.
I would not worry, you will have plenty of sunshine and even when it does rain for a brief period, a rainy afternoon in at CN is still a wonderful afternoon.