A breaker that trips after heavy rain is usually telling you that water is getting into a place it should not be. Outdoors, the most common causes are moisture in a light fixture, outlet box, junction box, conduit, or a damaged cable. When water reaches a connection or a device, it can create a short circuit or leakage path that trips the breaker or, if the circuit is protected, a GFCI device. The fact that it happens after rain rather than all the time is a strong clue that the problem is related to water intrusion somewhere on that outdoor circuit.
The first thing to check is whether the breaker is actually tripping, or whether a GFCI outlet or GFCI breaker on that same circuit is the device opening. People often call any power loss a breaker trip, but a GFCI trip usually points even more clearly to moisture, damaged insulation, or a faulty outdoor device. If you have outdoor receptacles, porch lights, landscape lighting, or a detached garage fed by that circuit, inspect each point for cracks, missing gaskets, loose covers, rust, and signs of condensation inside the box.
Outdoor fixtures are a frequent trouble spot. A light fixture with a bad gasket, a cracked lens, or a loose bulb socket can collect water inside the housing during a storm. The same goes for weatherproof outlet covers that are installed wrong or left open while something is plugged in. Conduit fittings and junction boxes can also admit water if the seals are poor. Even if the wiring itself looks fine, a small amount of moisture can be enough to trip protection devices, especially if the insulation is old or already damaged.
Another possibility is a compromised cable buried underground or run through a damp wall cavity. If the insulation has a nick, rainwater can seep into the damage and create a fault. In some cases, the issue only shows up when the ground is saturated because the wet soil lowers resistance and makes the fault easier to trigger.
I would avoid repeatedly resetting the breaker without finding the cause. If the circuit trips again right away, that suggests an active fault, and continuing to reset it could make the damage worse. The safest approach is to turn off the circuit and inspect the outdoor devices for visible water, then dry everything thoroughly before testing again. If the problem keeps coming back, an electrician should megger-test the wiring, inspect the outdoor boxes, and check whether the breaker or GFCI device has become overly sensitive.
If you have experience with outdoor circuits, share what you found and how you tracked down the leak or fault.
