The average price of a gallon of gasoline in the United States gained nearly 25 cents in the past four weeks, according to a survey released on Sunday.

Regular-grade gas climbed to around $2.02 per gallon in the March 20 survey, from $1.77 on Feb. 19, survey publisher Trilby Lundberg said in an interview.

The chief cause of the gasoline price rise was the recent increase in crude oil prices due in part to a weaker U.S. dollar, Lundberg said.

U.S. crude futures have soared by about 33 percent from $29.64 on Feb. 19 to $39.44 on March 18.

"We may see gasoline prices increase further even if crude oil prices do not continue rising because U.S. refiners have to prepare summer-grade gasoline to meet a May 1 deadline in most of the country," she said.

It costs more to make summer-grade gasoline, which has a lower vapor pressure to prevent smog, she explained.

In the Lundberg panel of around 2,500 gas stations in large cities in 48 states, the lowest average retail price for gas was in Newark, New Jersey, at $1.66 per gallon, and the highest was in Los Angeles, at $2.72 per gallon.