Costa Rica Rainy Season

During the rainy season in costa rica how much does it rain in a day?
My sister wants me to come down and see the turtles laying their eggs in Aug-Sept-I’m not sure if I should go? So undecided.
Where does she want to see turtles? September is the driest month on the Caribbean side and one of the wettest on the Pacific side. However, August still has lots of dry moments on the Pacific as well.
2pm Costa Rica Rain Storm