Summary (tl;dr)

"Coastal flood advisory" and "coastal flood warning" are trending as a powerful storm system brings heavy rain and strong winds, leading to coastal flooding risks across parts of the Northeast United States, North Carolina's Outer Banks, California's North Coast, and coastal British Columbia, Canada.

Essential Background

Coastal flooding occurs when seawater inundates low-lying coastal areas, a phenomenon primarily driven by storm surges, which are abnormal rises in sea level caused by strong winds and low atmospheric pressure associated with storms like hurricanes or tropical cyclones. High tides, particularly exceptionally high "king tides," can exacerbate these effects. In the long term, global climate change contributes to an increased risk of coastal flooding through rising sea levels and an uptick in the frequency and intensity of extreme weather events.

The Full Story

Today, December 19, 2025, several regions are under "coastal flood advisory" or "coastal flood warning" due to active weather systems. A significant storm is impacting the New York City metropolitan area and northern New Jersey, leading to coastal flood advisories for areas including Manhattan, Brooklyn, Queens, Staten Island, Long Island's southern shore, and Hudson, Essex, and Union counties in New Jersey. Heavy rain and strong wind gusts of 45-50 mph are anticipated to cause minor flooding on roads and in low-lying properties, with some vulnerable areas expecting up to a foot of inundation.

Concurrently, coastal flood advisories are in effect for Ocracoke Island and Hatteras Island in North Carolina, where 1 to 2 feet of inundation above ground level and localized ocean overwash are expected, potentially affecting NC-12. On the West Coast, a flood watch has been issued for California's North Coast, encompassing parts of Del Norte and Humboldt counties, due to anticipated excessive rainfall that could lead to riverine flooding, rockslides, and landslides. Meanwhile, coastal British Columbia, Canada, is experiencing ongoing elevated flood hazards and advisories through the week due to stormy weather and already saturated ground, with specific flood warnings and watches issued for various rivers and coastal regions.

Why It Matters

The widespread issuance of coastal flood advisories and warnings signifies immediate risks to property, infrastructure, and public safety in affected coastal communities. Even minor flooding can render roads impassable, disrupt commutes, and potentially damage homes and businesses. Such events underscore the growing vulnerability of populated coastal areas to the impacts of severe weather and rising sea levels, prompting residents to take precautions to protect property and avoid hazardous conditions like flooded roadways.

Geographic Location

• Manhattan, New York County, New York, United States (coastal flood advisory due to heavy rain and wind)
• Brooklyn, Kings County, New York, United States (coastal flood advisory due to heavy rain and wind)
• Queens, Queens County, New York, United States (coastal flood advisory due to heavy rain and wind)
• Staten Island, Richmond County, New York, United States (coastal flood advisory due to heavy rain and wind)
• Long Island's southern shore, New York, United States (coastal flood advisory due to heavy rain and wind)
• Hudson County, New Jersey, United States (coastal flood advisory due to heavy rain and wind)
• Essex County, New Jersey, United States (coastal flood advisory due to heavy rain and wind)
• Union County, New Jersey, United States (coastal flood advisory due to heavy rain and wind)
• Ocracoke Island, Hyde County, North Carolina, United States (coastal flood advisory with 1-2 feet inundation and ocean overwash)
• Hatteras Island, Dare County, North Carolina, United States (coastal flood advisory with 1-2 feet inundation and ocean overwash)
• Coastal Del Norte, Del Norte County, California, United States (flood watch due to excessive rainfall)
• Northern Humboldt Coast, Humboldt County, California, United States (flood watch due to excessive rainfall)
• Central and North Coasts, British Columbia, Canada (elevated flood hazards and potential for heavy precipitation)
• Sumas River, British Columbia, Canada (flood warning)
• Chilliwack River, British Columbia, Canada (flood warning)
• Lower Fraser River, British Columbia, Canada (flood watch for tributaries including Lillooet River, Fraser Valley, Fraser Canyon, North Shore Mountains)
• Kingcome River, British Columbia, Canada (flood watch)
• Englishman River, British Columbia, Canada (flood watch)