(NEXSTAR) — Temperatures around the country aren’t the only numbers reaching new heights. Gas prices are also heating up, reaching a nationwide average of $3.76 per gallon on Monday, according to AAA.

The situation is way worse out West. In California, the average is $5. Washington isn’t far behind at $4.95.

Gas prices typically rise in the summer, but the heat is making it even worse this year, industry experts say.

“You’ve got a lot of refineries that are coughing and wheezing. They’re not really geared to run with 10 or 15 days with 100-degree temperatures in a row,” explained Tom Kloza, global head of energy analysis at OPIS, in an interview with NBC News.

When refineries don’t run at their full capacity, less and less gasoline is produced. A tighter supply naturally means higher prices.

The biggest drop in production has been at refineries on the West Coast, USA Today reports.

Things could get worse before they get better, predicted Patrick De Haan, lead petroleum analyst at GasBuddy. He said he wouldn’t be surprised if gas prices rise another 15 cents in the next few weeks.

“As we get into fall, things should cool back off,” De Haan said. “The major wild card is Saudi Arabia and Russia because there is word that Saudi Arabia may extend its cut of oil production into September.”

Oil production cuts in the Middle East have already been driving up the price of crude oil, which in turn makes gas more expensive.

A bad hurricane season would also disrupt refineries on the Gulf Coast, spiking prices even higher.