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Winter flooding by region: atmospheric rivers, nor'easters and ice jams

Flooding isn't just a summer and hurricane-season problem. In much of the country, winter brings the biggest floods of the year. Here's what drives them in each region.

Reviewed October 2026

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West Coast: atmospheric rivers

From about November to March, long, narrow bands of moisture from the Pacific, called atmospheric rivers, bring days of heavy rain to Washington, Oregon and California, and heavy snow in the mountains. Several in a row can swell rivers, flood low-lying neighborhoods and trigger mudslides, especially below hillsides burned by wildfires. A warm storm that brings rain on top of snow adds snowmelt to the runoff.

Southwest and Southern Plains

Winter rain is less common, but dry, hard ground and steep terrain mean a heavy storm can cause flash flooding quickly, especially in desert washes and burn scars. NOAA's winter outlook favors a wetter winter here this year. See the winter flood outlook.

Gulf Coast and Southeast

Winter storms moving along the Gulf can drop several inches of rain in a day. Flat land and high water tables mean water drains slowly, so street and river flooding can last for days. This region also tends to be wetter in El Niño winters.

Mid-Atlantic and Northeast: nor'easters

Nor'easters are strong coastal storms most common from October to April. Onshore winds push seawater inland as coastal flooding, which is worst when the storm arrives with a high tide. Heavy rain can flood streets and rivers inland at the same time.

Midwest, Great Lakes and the North: snowmelt and ice jams

In late winter and early spring, ice jams can block rivers as the ice breaks up, backing water up behind them with very little warning. Heavy rain on deep snow, or a sudden thaw, can push rivers over their banks. River gauges are the best early warning: see river flood stages.

Anywhere it freezes: burst pipes

The most common winter water damage isn't a flood at all. It's a frozen pipe that bursts. See frozen or burst pipe? What to do.

Get ready before the storms

  1. Check your address for its flood zone, alerts in effect and nearby river gauges.
  2. Turn on free flood alerts for your home with the Flood.global app.
  3. Look at flood insurance now. A new NFIP policy usually takes 30 days to start. See how much flood insurance costs.
  4. Clear gutters and storm drains and test your sump pump. See how to prepare for a flood.

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