U.S. gasoline prices rose by slightly more than 10 cents per gallon in the past two weeks, the biggest jump since last August, an industry analyst said Sunday.

The weighted national average for all three grades of gasoline was just over $1.96 per gallon on Friday, according to Trilby Lundberg (search), publisher of the biweekly Lundberg Survey (search), which regularly polls 8,000 gas stations across the United States.

Tight gasoline supplies and rising demand at a time when seasonal environmental regulations cause a price adjustment are responsible for increase, Lundberg said.

"Those regulations have both a cost and supply impact on refiners," said Lundberg. "We get less gasoline out at a higher cost just when we need more of it. Meanwhile, tighter regulations make it tougher for importers to bring in additional supplies."

The nation's economic growth has also increased demand, contributing to the rising prices, Lundberg said.

The average price of gasoline has broken all-time record highs for two months straight, although the average price remains about 90 cents a gallon lower compared to the peak gas price in March 1981 when adjusted for inflation, Lundberg said.

Crude oil prices reached a 13-year high of $40 a barrel on Friday, the highest since Oct. 11, 1990, in the run-up to the 1991 Gulf war (search). Prices for crude oil and for gas at the pump are unlikely to decline anytime soon, Lundberg said.

The national weighted average price of gasoline at self-serve pumps on Friday, including taxes, was about $1.93 for regular, $2.02 for mid-grade and $2.11 for premium.

San Diego had the highest average price of any city, with self-serve regular selling for an average of $2.25. The average for self-serve regular in California was $2.21.