The instinct when a GFCI trips repeatedly is to replace the GFCI. Nine times in ten the device is fine and is reporting a genuine leakage current somewhere on the circuit.
What the device is measuring
A GFCI compares the current going out with the current coming back. If more than a handful of milliamps fails to return, it assumes the missing current found another path to earth, which in the worst case is a person. It trips in well under a second. That sensitivity is the whole point, and it is why small amounts of moisture set it off.
Work outward from the wet things
Start by unplugging everything on the circuit and resetting. If it holds, add loads back one at a time. Outdoor outlets, garage freezers, bathroom heaters and anything with a heating element are the usual culprits. Old appliances with degraded element insulation leak steadily and will trip a healthy device every time.
If the device trips the moment it is reset with no load connected, stop and call someone. That is a hard fault, not a nuisance one.
Then look at the boxes
If the trip persists with nothing plugged in, the leakage is in the wiring. Outdoor boxes with failed gaskets collect water. Buried joints in a wall cavity get damp. A staple driven slightly too hard thirty years ago nicks the insulation and only becomes a problem when humidity rises. This is where testing beats guessing: an insulation resistance test finds the segment in minutes.
What not to do
Do not swap the GFCI for a standard outlet to make the tripping stop. You will have removed the protection and kept the fault.
Send us a photo
Open the panel door, photograph the label, and we will tell you the make, the age, and whether it needs replacing.