That means that the estimated barometric pressure at the center of the hurricane is 902 millibars, or 26.63 inches of mercury. "Standard" atmospheric pressure is 1000 millibars, or 29.92 inches of mercury. The lower the pressure at the center of a hurricane, the stronger the winds are and the stronger the storm generally is, so it's used as an indication of how powerful a hurricane we're dealing with.
902 mb is exceptionally low. I think that makes Katrina the fourth or fifth strongest Atlantic hurricane ever recorded...with twelve more hours of 90-degree water between it and the coast.
Dear God.
}:-)4
I believe Gilbert in 1988 had 185 MPH winds and a reading of 888. It his Jamaica and then the Yucatan. There may have been one other hurricane with a lower reading, but I cannot rember which it was.