(Bloomberg) -- Florida is facing a potential squeeze on fuel supplies as shipments into the state slow just as demand is rising from consumers preparing for the threat of a major hurricane. 

Demand is surging for gasoline as Floridians fill up for possible evacuations, according to Ned Bowman, executive director of the Florida Fuel Marketers Association. Diesel buying is also up, with the fuel needed for backup power generation. 

But meanwhile, barge traffic moving fuel from the US Gulf Coast into Florida is down as transport slows ahead of the storm. The state is mainly supplied via waterborne shipments from refiners in Texas and Louisiana. Ports of Tampa, Manatee, St. Petersburg and Fort Myers in Florida have halted incoming ships. 

Tropical Storm Idalia is strengthening, threatening to strike Florida’s west coast Wednesday as a major hurricane.

The potential fuel squeeze comes as government data show that stockpiles of distillates, which include diesel, are at the lowest level ever for this time of year in the lower Atlantic coast region, including Florida. Gasoline stockpiles at the lowest seasonal level in more than a decade. 

Read More: Florida Faces Major Hurricane Threat as Idalia Strengthens 

Fuel distributor Mansfield is requiring 48 hours-notice for new deliveries in Florida, south Georgia and coastal South Carolina. Deliveries will halt as wind speeds pick up, as driving the trucks becomes hazardous at wind speeds above 30 miles (48 kilometers) per hour. Idalia’s winds are forecast to reach Category 3 strength at 115 mph. 

Diesel prices edged up to $4.407 a gallon in Florida overnight, from $4.380 a day earlier, according to data from the American Automobile Association. Average gasoline costs were little changed at $3.702.

(Updates scope of delivery notice in penultimate paragraph. An earlier version was corrected to reflect a corrected notice period from Mansfield.)

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