The conversion to summer-blend gasoline, statewide refinery issues and a rise in crude oil prices have sent California prices to new highs, according to the latest AAA Northern California monthly gas survey.

Many metro areas in Northern California saw an increase of at least 31 cents per gallon over the past month.

In San Mateo, gas prices are up 37 cents in a month, to an average of $4.03 per gallon. Northern California gas prices are now averaging $3.95, a change of 39 cents in price from last month's report.

California's average price for a gallon of regular unleaded gasoline is $4.06, up 45 cents since last month's AAA report. Gas prices today are 22 cents more expensive than California's average price on this date last year. Among all 50 states, California has the second highest state average price for regular, unleaded gasoline. Hawaii is the highest at $4.24, according to AAA.