Gas prices across Arizona increased from last week. Triple-A Arizona says the average price of gas jumped three cents a gallon this week to $3.14 a gallon. In Flagstaff, the average price of gas was up about a cent a gallon to $3.42 this week. Some stations are selling gas for $3.31 and lower. In Prescott, the average price of gas was also up about a cent from last week to $3.15 a gallon. Some stations are selling gas for $3.04 a gallon and lower. Triple-A says with demand increasing and supplies tightening, there has been some fluctuation in gas prices this week across the country. Oil prices remain high, hovering around $70 a barrel, which is also keeping the average price of gas above three-dollars a gallon.