Well the area under the wipers is certainly one possibility. That area has a drain and leaves and things can clog it resulting in leaks. That would be a good thing to check first. If you add a liter or two of water in there you should see it come out under the car.
However it can also come from a blocked A/C condensation drain, or a heater core leak or a sun roof leak (if you car has a sun roof that would be #1 on my list and it is usually caused by a blocked drain).
Note that blocked drains can usually be safely opened by finding the outlet (or inlet for the sun roof) and carefully using some string trimmer line to clean it out.
One last one is a rust problem, possibly from the trunk, but that is not likely with a car less than 10 years old.