flight Snowcloud Five was lost while making a penetration into the hurricane's eye, another flight early on September 27 reported a minimum pressure of , with winds in excess of "by a large and incalculable amount." The hurricane was estimated to have intensified to Category 5 hurricane intensity—the highest rating on the modern-day Saffir–Simpson hurricane scale—at 1200 UTC on September 27, while in the western Caribbean Sea. Janet continued to intensify afterwards, eventually reaching its peak intensity with maximum sustained winds of , with gale-force winds having expanded to at least away from the center of the hurricane. Janet maintained peak intensity as it passed over the Swan Islands before making landfall in extreme southern Quintana Roo, Mexico, just east of Chetumal, Mexico. In that city, a barometer indicated a minimum barometric pressure of in the eye of Janet. At the time, this was the second-lowest pressure ever recorded on land in a landfalling Atlantic hurricane, behind the 1935 Labor Day hurricane, though Janet was later surpassed by hurricanes Dean and Gilbert, which also made landfall on the Yucatán Peninsula as Category 5 hurricanes. Once over land, Janet considerably weakened to a Category 2 hurricane with winds of . After crossing the Yucatán Peninsula with a forward speed of , the hurricane emerged into the Bay of Campeche by 1600 UTC on September 28. The weakened hurricane marginally intensified as it crossed the Bay of Campeche to a secondary peak intensity of with a minimum central pressure of . Janet eventually made its final landfall north of the city of Veracruz by 2200 UTC on September 29 as a Category 2 hurricane. After moving inland, the hurricane became quickly disorganized due to the highly mountainous terrain of Mexico, and as a result the Weather Bureau issued its last advisory on Janet. The weakening system degenerated to tropical storm strength by September 30, and later dissipated over central Mexico by 0600 UTC that day. Janet's remnant circulation contributed to the development of a disturbed area of weather off the western coast of Mexico that would subsequently develop into a tropical storm on October 1. Preparations Caribbean Islands Upon Janet's formation east of the Windward Islands, the Weather Bureau office in San Juan, Puerto Rico advised small craft to remain in port and vessels in the path of the developing storm to exercise caution. After a reconnaissance flight reported much stronger winds