Rainy and 40ish all weekend here ...
We've had a few instances over the last couple of years with the GFI popping. I read somewhere that GFIs over the years get that way.
We had a lot of rain here last month.
The GFI popped in the trailer & wouldn't reset.
Bought a new one & installed. It popped & wouldn't reset.
Started pulling outlets and replacing. I wanted to pull them anyway to trace and do some rewiring. The outlets were the pos kind that the wires push into.
After I opened the exterior outlet and removed the pos outlet the GFI problem went away. There seemed to be a couple of excess "cuts" in the insulation and I speculate that moisture trapped in there was the culprit.
You could have a moisture problem that is popping the GFI. If the problem persists at home, a hair drier on the exterior outlet(s) might help. If you wind up pulling and replacing the exterior outlet beware that it is not a simple job. My pos outlet was secured by plastic "ears". They didn't work with a real outlet. I wound up getting a "mud plate", cutting it down enough to fit in the hole and securing the new outlet to that.
New "real" box and outlet for the refrig connected to the same circuit breaker as the water heater. Now I can kill the AC, MW, WH & refrig when dry camping.
All wall outlets connected to one circuit breaker through a transfer switch so they can be powered by my inverter. Also installed the inverter.
New "real" box and outlet for the Power Converter and a dedicated circuit breaker for it. The Power Converter lives under the stove and the outlet is behind a door. This gives me a outlet on a separate circuit for the electric heater, toaster oven or coffee pot if they cause problems on the same circuit as TV & etc.
There was a box under the pos outlet for the power converter with a blank cover. Inside the box a ac house wire came in, was connected to a rubber covered cable that went under the floor. I have no clue what that is. It is not anything mentioned above.