Hurricane Gustav was officially back at hurricane strength on the Saffir-Simpson scale as of August 29, 2008. The 5 day outlook for the storm meant New Orleans would get either a direct or indirect hit. Warm ocean temperatures and a low wind shear environment made conditions ripe for a massive storm. There was some indication that wind shear was increasing, which could have slowed the development of Gustav. In addition, meteorologists were watching a high pressure zone over the United States which would alter the path of Gustav.
A location known as the Bermuda High is partly responsible for Gustav's path into the Gulf. A video demonstration of the Bermuda high shows how storms can get bumped into the Gulf. After a hurricane passes, the warm waters will cool as can be seen in satellite images. Ocean water temperatures need to be 80+ degrees and the layer must be relatively thick to sustain a hurricane and make the hurricane grow. As the hurricane gains power, wind shear becomes a great 'hurricane breaker'. Unfortunately, there was little wind shear in the Gulf of Mexico meaning Gustav would later become an intense storm.