A strong area of high pressure over the western Gulf of Mexico forced the storm to turn southwestward, back to the Mexican coastline. Increasingly deep cloud cover formed over the storm in response to a favorable environment over the Bay of Campeche. Late on October 3, forecasters at National Hurricane Center noted a statistical rapid intensity index indicating a 49% chance of Stan undergoing rapid intensification before its final landfall. This intensification did take place within 12 hours before the hurricane moved onshore. Overnight, the structure of Stan rapidly improved, with a banding eye-feature developing within unusually deep convection with cloud-top temperatures measured at by infrared satellites. Following this development, National Hurricane Center upgraded the storm to a Category 1 hurricane on the Saffir–Simpson Hurricane Scale. Around 1200 UTC on October 4, Stan made landfall near Punta Roca Partida, with winds of 80 mph (130 km/h). The storm also attained its lowest barometric pressure of 977 mbar (hPa; 28.85 inHg) at this time. Not long after moving over the mountainous terrain of central Mexico, Stan rapidly weakened to a tropical depression and fully dissipated early on October 5 over the state of Oaxaca.