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Winter Floods: Why They Happen

Floods are traditionally associated with natural disasters such as hurricanes that take place in warmer climates. But did you know that cold winter temperatures can also cause flooding?

There are many conditions that can cause an overflow of water. You must stay alert even when the conditions seem to lend themselves to a frozen winter rather than a flood.

Winter Flooding Causes

Coastal Flooding

Strong winds affect coastal water levels, no matter the season. Winter storms can be as harmful as tropical storms. According to FEMA, winter storms can cause widespread tidal flooding and severe beach erosion along coastal areas. Strong winds can push water levels up, causing storm surges. In lakes, even once the water levels return to normal, a pendulum effect can cause water levels to rise on alternating sides, giving way to floods on multiple sides.

Don’t let your guard down during winter. Keep your eye out for severe weather alerts and be wary of strong winds near bodies of water.

Ice Jams

An ice jam, or ice dam, happens when chunks of ice clump together to block the flow of a river. A rise in the water level or sudden thaw breaks the ice into large chunks. These can become jammed in all sorts of natural or man-dame obstructions which can result in severe flooding. They can develop near river bends, mouths of tributaries, points where the river slope decreases, downstream of dams and upstream of bridges or other obstructions. These types of ice jams can be very dangerous for communities that are near rivers.

Ice jams can also happen on roofs. When a considerable amount of snow is collected on a roof, heat from the house can cause it to melt quickly and pool underneath roof shingles where it can cycle between melting and refreezing, causing ice dams that lead to rot or mold.

To prevent ice dams from forming on your roof, monitor the amount of snow on your roof at all times. If you have a foot or more of snow on your roof, you’re going to want to remove it with a snow roof rake or a snow shovel. But be very careful, this can be a dangerous endeavor.


A white winter can be beautiful, that is until the snow starts to melt. When water pools around the house, it can go directly into the ground around the foundation of your home.

Be especially alert around basement windows or laundry vents; snowmelt water doesn’t flow along the same channels as traditional rain which can lead to flooding in places where you wouldn’t expect.

Sudden temperature changes can also lead to larger-scale dangerous snowmelts. As FEMA warns, “a sudden thaw can produce large amounts of runoff in a short period of time. Because the ground is hard and still frozen from low winter temperatures, water cannot penetrate and be reabsorbed. The water then runs off the surface and flows into lakes, streams and rivers, causing excess water to spill over their banks.”

Frozen Pipes

When cold water freezes inside pipes, it can lead to pressure buildup that will eventually cause a pipe to burst. To prevent pipes from bursting, insulate pipes in potential freeze areas, seal holes letting cold air into your home, and leave the water on trickling slowly on colder days and nights; the static water keeps the pipes from freezing and bursting.

Be alert if your water suddenly stops or the drain starts to smell, these may be signs of frozen pipes. Installing a pipe insulation sleeve will help you protect your home.

It’s always a good idea to keep your flood insurance policy active during winter, you never know what colder temperatures may have in store.

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