Gas prices are returning to below the $4 mark on the north side of the Treasure Coast this week. 

GasBuddy says the average cost in Indian River County was $3.99, dropping as low as $3.75 within Vero Beach city limits. 

The trend for St. Lucie County is about $3.80 a gallon, the web site states.

Motorists are fueling up higher in Martin County, with about $4.20 per gallon. 

One month ago, Treasure Coast drivers were paying an average of $4.35 per gallon. 

Observers at AAA said steady decline is because of lower domestic demand for gas and a lower global price for oil. The cost of a barrel of oil is about $90, down from around $110 two weeks ago.

“Global economic headwinds are pushing oil prices lower and less expensive oil leads to lower pump prices,” said Andrew Gross, AAA spokesperson. “And here at home, people are fueling up less, despite this being the height of the traditional summer driving season."

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Patrick De Haan, head of petroleum analysis at GasBuddy, predicted the decline, although he said factors around the world could drive prices up again.  

“If we do tip into a recession, that could push prices down," he told USA Today. "If there is data that we aren’t going to tip into a recession, that could cause prices to go up. But really, I'm worried about the unforeseeable events like refinery shutdowns due to a hurricane or other factors.”

Florida joins most southern states with gas prices hovering around $4 per gallon, compared with the West Coast, where California motorists are fueling up at nearly $6 a gallon and other states there are paying about $5.30 a gallon. 

In the Sunshine State, the panhandle has the cheapest gas, with several stations in Pensacola and Panama City offering gas under $3.60 per gallon. 

Staff writers Mauricio La Plante and Corey Arwood contributed to this report. 

Lamaur Stancil is the Treasure Coast regional economy reporter covering business and industries, including retail, tourism and hospitality. Contact him at 321-987-7179 or lamaur.stancil@tcpalm.com and follow him at Lamaur Stancil on Facebook and @TCPalmLStancil on Twitter.