Hurricane Barbara picked up speed Wednesday as it moved toward Mexico's southern Pacific coast.
The hurricane has reached maximum sustained winds 75 miles-per-hour, with the US National Hurricane Center predicting it will make land near the port of Salina Cruz, home to Mexico's largest oil refinery.
Four to 12 inches of rain is forecast, along with a storm surge of up to five feet above normal tide levels.
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A hurricane warning has been issued between Puerto Angel and Barra de Tonala. Around 4,000 people in Chiapas state are being evacuated as Hurricane Barbara approaches.
Officials in the southern state of Oaxaca rushed to prepare emergency shelters, which were being set up across 20 towns and hamlets. Classes for school children in coastal communities were canceled for the rest of the week.
Along with Oaxaca, Mexico's national meteorological society warned the states of Guerrero, Chiapas, Veracruz, Tabasco and Campeche to be prepared for intense rain, strong winds, floods, landslides and rising rivers.