Camarillo, Calif. ? Retail gas prices plunged an average of 23 cents nationwide in the past two weeks, marking a return to pre-Hurricane Katrina levels, according to a survey.

The weighted average price for all three grades declined to $2.45 a gallon on Friday, said Trilby Lundberg, who publishes the semimonthly Lundberg Survey of 7,000 gas stations around the country.

Self-serve regular averaged $2.43 a gallon nationwide. The price for midgrade was $2.53, while premium-grade hit $2.63.

The average pump price for all three grades on Aug. 29, the day Katrina made landfall on the Gulf Coast, was $2.65, according to the survey.