If you have a slider window, it is possible that the weep holes may be clogged with dirt/debris. If you look at the window frame on the outside there should be a couple of plastic weep hole covers on the frame below the windows sliding tracks. Sometimes you need to remove the covers and clean the holes. The holes should open up to the slider tracks..
If the weep holes are plugged, the water from heavy rains builds up in the slider tracks and eventually has no where to go other than spill into the inside of the frame.
Also check for same weep hole covers on the top of the window frame, those sometimes are present to allow for the window to be installed for a flipped direction of opening.. The top weep covers sometimes will leak and a dab of caulking tends to correct that.
It is possible during extreme hard rains that the weep holes simply get overwhelmed and in that case, not much can be done about that..
Don't caulk to bottom weep holes shut..
