(NEXSTAR) — As the national average has started to creep back up, gas prices have jumped as high as 40 cents over the last week at some fuel stations. AAA reports prices are up 4 cents—to $4.16 for a gallon of regular gasoline—since Monday.

Over the last week, Delaware has seen the largest price increase at more than 20 cents per gallon. Maryland, Ohio, Indiana, Michigan, and Florida have also seen big jumps. Fluctuating oil prices and tight gas supply are to blame for this most recent spike in prices, according to AAA. They expect the cost of gas to keep increasing as oil prices stay above $100 per barrel.

In recent weeks, gas prices dropped some 20 cents after hitting a high of $4.33 per gallon in mid-March. It was the highest-ever recorded average price. As a comparison, the price for a gallon of regular gas one year ago was $2.89.

However, it may not hold that record for long, according to Tom Kloza, the global head of energy analysis at the Oil Price Information Service. “The market is still scary,” he told CNN. “I would not be laying odds on DraftKings that $4.33 will be the highest price over the next few months. We may go higher.”

At the end of March, Pres. Joe Biden announced a plan to release 1 million barrels of oil from the U.S. reserve in an effort to lower gas prices. Temporary relief came shortly thereafter. “Americans should already be seeing the savings,” Biden said. “Although it’s only gone down about 18 cents, the savings are starting.”

Speaking with NEWS10’s Washington correspondent Hannah Brandt, AAA spokesperson Andrew Gross said, “There are very few weapons in the president’s arsenal they can use [to impact gas prices], and he’s pretty much trying everything.”

What happens from here? It’s difficult to know, according to Todd Staples, president of the Texas Oil and Gas Association. He told NEWS10’s sister station in Austin that it’s difficult to predict when there will be a consistent and stable price decline due to the Russia-Ukraine conflict.

“It’s frustrating for people filling up at the pump because they want affordable gasoline,” said Staples. “Our industry is not being held by all of the volatility.”