So on hiking days, I look out my window to see if the Volcan Baru is covered in clouds or listen for rain. If the Volcan Baru is not covered by the clouds it's a good morning for a hike.
Best to do a hike in the morning at this time of the year otherwise, you will be rained out. Twice, we have finished right on time. Always pack rain gear as it's better to be safe than sorry.