It was a week of record gasoline prices in the US last week, with and things could get worse for America’s thirsty vehicles. Oil prices climbed above $65 a barrel amid concerns that U.S. refiners are not producing enough gasoline to meet peak summer demand. The volatile situation in Nigeria is also keeping the markets jittery.

With the Northern Hemisphere’s summer driving season set to begin in just over a week, energy traders have been concerned that gasoline supplies won’t meet demand. A string of planned and unexpected refinery shutdowns have fuelled such worries.

“It will continue to be an issue. If demand is strong this season, it’s going to be hard to keep up and it will push prices [up],” said Tobin Gorey, a commodity strategist with Commonwealth Bank of Australia in Sydney.