At $3.094 a gallon, Seattle area consumers paid 12.7 percent more than the $2.745 national average in August 2015. A year earlier, consumers in the Seattle area paid 9.6 percent more than the national average for a gallon of gasoline.egional Commissioner Richard J. Holden noted that area gasoline prices were down 78.7 cents compared to last August when they averaged $3.881 per gallon. Seattle area households paid an average of 10.2 cents per kilowatt hour (kWh) of electricity in August 2015, up from the 9.6 cents per kWh in August 2014.