Hurricane Michael made an “unprecedented” landfall on the northern Gulf coast of Florida Wednesday afternoon (Oct. 10). Just as it came ashore, meteorologists with the National Hurricane Center (NHC) released data showing that the rapidly strengthening storm made landfall as the third-strongest hurricane in continental U.S. history. It edged out Hurricane Katrina, which devastated the Gulf coast in 2005.

When meteorologists talk about the power of hurricanes, they talk about barometric pressure, not wind speed. A hurricane is an intense low-pressure system, and, as National Geographic reported in 2015, the extent of atmospheric-pressure drop in the storm is the best meteorological proxy for the storm’s overall strength and intensity.

Katrina made landfall in 2005 with a pressure reading of 920 millibars (about 8 percent lower than the average 1,000 mb air pressure at sea level), according to the NHC. The final recording from inside Michael before landfall was one tick lower: 919 mb. Two hurricanes in history have made landfall in the continental U.S. with lower pressures: Camille, which carved up the Mississippi coast at 900 mb in 1969, and the Labor Day storm that struck southern Florida at a peak intensity of 892 mb in 1935.