GFI that trips when it rains
 

Does anyone know how to prevent a gfi switch located on a wall outside from tripping when it rains badly.

If it is outside, it should be a weatherproof type that has plastic covers or a plastic box around it to keep out the water. If not, I would take a photo of it and ask Home Depot or ACE Hardware if they have a replacement.

1 Is there something pluged in ? If there is it's doing it's job just cover exposed plug with plastic bag seal out the rain
2 If not and it's in a weather proof enclosure it needs replacing.

OP, if the home is within the first year, call home warranty to have repaired. If not, I would go to one of the big box stores, and get a new outside cover, I like the ones with a big plastic cover instead of the small individual covers. It should be a simple task to remove the old cover and install a new one. If the problem continues, there may be another problem, either another outside receptacle or damaged wiring. You can get your house plans from Sumter county building department and one of the sheets shows the house wiring. This will give you an idea of where to look.
Hope this helps, and send me a PM with your contact info if you would like to discuss further.

At my house they had 2 GFI's on the same circuit and the outside terminal one was always tripping so I replaced it with a normal plug which solved the problem. The new plug was "covered" by the inside GFI. I would say in general that the GFI's I have had and installed can be somewhat of a problem. The cheaper ones tend to trip more often.

Mine does it when I have my outside Christmas lights up. I recently discovered that it was being caused by two spotlights that I had on my palm tree. I unplugged those two light, taped up the extension cord outlets and everything it fine.

If you have anything plugged in outside, I would check that.

There should never be 2 GFCI on the same circuit, IF the wiring is on the protected side of the first GFCI. If that is the way this was wired, and you removed the second GFCI, you are NO LONGER protected using the outside (second) GFCI. Please double check your wiring. In our house (2013 vintage), there are 3 GFCI in the garage that protect ALL of the outside receptacles including the ones in the lanai at the back of the house. The bathrooms have their own GFCI units.

could be lamp post if on same circuit

I know there shouldn't have been 2 GFI's on one circuit but there was and the second one was always kicking the first one off. I have built 3 houses by myself and am aware of what I am doing but thanks for the input anyway.

My covers are metal and spring loaded. Most likely moisture getting in when it rains if it only happens during rain. You should be able to see it when you lift the cover of course when it’s tripped. I would also check seal between the cover and the house. Make sure it sealing and not deteriorated leaking behind the cover?

Another thing what even you got plugged in has to be waterproof. If you got extension plug in laying out on the ground where moisture or water can get into the connection it will trip it. You can cover it up or wrap with plastic bag so the water don’t get in.

I must string about 100 sets of Christmas lights (50 lights per string) at Christmas time. Should I wrap up each connection when I connect six sets together? Reason why I ask is that I have the GFI outlets trip when it rains when my Christmas lights are strung on the shrubs.

Until everything dries out, those outlets will not reset. Sometimes I have to wait a day or two (with no rain) for the outlets to be reset.

If all I have to wrap up is the connections that are lying on the ground, then that is doable and I will give that a try come this December.