Why do my outdoor GFCI outlets keep tripping when it gets cold outside?

Outdoor GFCI outlets that trip repeatedly in cold weather are almost always reacting to moisture infiltration caused by condensation, ice formation, or a failing weatherproof cover — the GFCI is doing exactly what it is designed to do by detecting ground fault current, but the underlying moisture problem needs to be fixed. This is one of the most common outdoor electrical complaints from GTA homeowners between November and March.

GFCI devices are engineered to detect imbalances as small as 4 to 6 milliamps between the hot and neutral conductors. When moisture — even a thin film of condensation — forms on the receptacle contacts or inside the wiring connections, it creates a tiny leakage path to ground that the GFCI picks up immediately. In Toronto's climate, this happens frequently because of the dramatic temperature swings between day and night during fall and spring. A sunny afternoon warms the air inside the outlet box, then a cold night causes that warm, moist air to condense on the cold receptacle contacts. The GFCI trips, and you walk outside in the morning to find your holiday lights, block heater, or security camera are off.

The first thing to check is the weatherproof cover. Outdoor GFCI outlets require an in-use cover (sometimes called a bubble cover or while-in-use cover) that maintains a weatherproof seal even when a cord is plugged in. The older flip-up covers only protect the outlet when nothing is plugged in — they are no longer code-compliant and should be replaced. If the cover gasket is cracked, compressed, or missing, moisture gets in freely. A replacement in-use weatherproof cover costs $8 to $15 and is a straightforward swap that most homeowners can handle.

If the cover is in good condition and the GFCI still trips in cold weather, the problem may be inside the outlet box. Open the cover (with the circuit turned off at the panel) and look for signs of moisture, corrosion, or ice inside the box. Green or white corrosion on the wire connections or receptacle terminals indicates chronic moisture exposure. The box itself may not be properly sealed — check that all conduit entries have weatherproof fittings and that the box mounting is tight against the wall with no gaps where water can seep behind it.

Another common cause is a worn-out GFCI device. GFCI receptacles have a lifespan of about 10 to 15 years, and outdoor units degrade faster due to temperature extremes and moisture exposure. An aging GFCI becomes hypersensitive and trips on increasingly small leakage currents. If your outdoor GFCI is more than 10 years old and trips frequently, replacing the device ($15 to $25 for a WR-rated outdoor GFCI receptacle) often solves the problem.

Finally, the tripping may not be caused by the outlet itself but by the device plugged into it. Block heaters, outdoor fountains, pond pumps, and old holiday light strings can develop small insulation faults that only manifest when cold temperatures make the wiring brittle. Try plugging the device into an indoor GFCI outlet — if it trips there too, the device is the problem, not the outdoor outlet. If persistent GFCI tripping continues after checking covers and connections, have a licensed electrician diagnose the circuit. Toronto Electrical Repair can connect you with a local pro for a service call.