As Tropical Storm Nicholas moves over the South, it’s expected to dump as much as 20 inches of rain. That much rainfall could lead to flash floods, a deadly threat usually associated with hurricanes. Nicholas, a Category 1 hurricane at landfall, could be a “major blow” to Texas and Louisiana, already sodden from Hurricane Ida, according to AccuWeather.

But looking only at a storm's ranking can be misleading, experts say. As Hurricane Florence neared the North Carolina coast in 2018, its severity was repeatedly downgraded—from a Category 4 to a Category 1. Its winds diminished, but the storm grew larger in size, slowed down, and unleashed torrential rain that led to major flooding.

While the worst