Several cities in southeastern North Carolina saw historic rainfall Monday as a potential tropical cyclone swept through the area. Rainfall in Carolina Beach, along the coast near Wilmington, set a particularly notable record. According to the National Weather Service, 18 inches of rain fell on Ocean Boulevard over the course of 12 hours — a phenomenon that only happens “once in a thousand years,” according to meteorologists.

“Historic rain has fallen today in Carolina Beach, Southport and BSL,” the weather service in Wilmington wrote in a social media post shared Monday afternoon. “Volunteer gauges have recorded over a foot of rain since midnight.”

The weather service, citing data from the National Oceanic and Atmospheric Administration, noted that the area averages 12 inches of rain in a 12-hour period about once every 200 years. That unusual threshold was reached in a number of places where gauges collected rainfall from midnight Monday through noon.

The 18 inches recorded on Ocean Boulevard near Carolina Beach was the highest rainfall associated with the weather system. After that, areas around the nearby Snows Cut Bridge, Sunny Point Military Terminal and Boiling Springs Lakes all received more than 14 inches in a half-day. Parts of Southport and the city of St. James each recorded more than a foot of rain, while Leland, which is closer to Wilmington, saw nearly 7 inches. Rainfall in Wilmington itself was considerably lower, with a measurement taken at the Wilmington airport showing just over 3 1/2 inches.

Dangerous flooding and strong, gusty winds battered parts of southeastern North Carolina on Monday as the National Hurricane Center warned that some of the effects from the storm, which it designated Potential Tropical Cyclone Eight, could be “life-threatening.” At 5 p.m. EDT that afternoon, meteorologists estimated that the system would bring another 4 to 8 inches (10 to 20 centimeters) of rain to parts of the region by late tonight, with some places possibly getting as much as 10 inches (25 centimeters).

The weather service in Wilmington shared images of some of the damage caused by Monday’s rain and flooding. In Brunswick County, part of a road collapsed due to the weather, sending fragments into a pit of muddy water that pooled below.

“There have been significant road closures in Brunswick County as a result of today’s heavy rainfall and flooding,” the service said.

Meteorologists said no additional rain was expected Tuesday in the areas hit Monday, and multiple flash flood warnings issued earlier in the area expired before midnight.