On several occasions, we've had multiple GFCIs that have tripped. Septic tank pump, bathroom outlets, garage outlet (the ONLY outlet on the circuit with nothing plugged into the outlet), etc. Sometimes one will trip, sometimes many will trip.

We've had some rather strong T-storms of late with lots of lightning. Could nearby lightning strikes or power surges cause this? Dirty power from the local power company?

Thanks for any advice or theories!