Portland, ME – Residents from Portland to Bangor could soon hear mysterious booming sounds echoing through the night as winter’s first deep freeze arrives. Experts say those startling noises are likely frost quakes — sudden cracking events in the frozen ground caused by rapid temperature drops.
According to the Maine Geological Survey, frost quakes, or cryoseisms, occur when rain or melting snow saturates the soil, then freezes too quickly as temperatures plunge below zero. The expanding ice builds pressure until it fractures the ground — releasing a sharp pop or rumble that can sound like an explosion or distant thunder.
Meteorologists say this winter’s pattern of mild, wet days followed by arctic cold fronts makes southern and central Maine particularly susceptible. Conditions are ideal when the ground is soaked but there’s little snow cover to insulate it — a setup expected later this week as temperatures across Portland and Bangor dip into the single digits overnight.
While frost quakes are brief and highly localized, they can startle residents and occasionally leave small surface cracks in pavement or foundations. Most occur between midnight and dawn, when the air is coldest and ground pressure peaks.
Experts recommend improving yard drainage and clearing standing water before major freezes to minimize frost-quake risk near homes.
So if you’re awakened by a thunder-like boom on a calm, icy night — it’s probably not construction or fireworks. It’s winter itself, cracking beneath your feet from Portland to Bangor.
