Time for your weekly update on gas prices, and you may have noticed a big spike over the last week.

Here in Billings, prices jumped a whopping 12 cents in the last week to $3.77 a gallon!  The national average only climbed 4 cents in the last two weeks to $3.92, but the Huffington Post reports that prices could top the $4.00 mark this week!

So why the surge?  It’s that time of year when refineries reduce their output to make a cleaner blend of gasoline for the summer.

This year’s spike is more extreme than in the past because three refineries that serve the East Coast were shut down last fall and another may be closed in July.  That has threatened supplies and pushed prices up all across the country.  There is some good news though!  The summer gasoline blend improves fuel economy by one to two percent which means you’ll get a little more from that pricey tank of gas!

In case you are wondering, the Lundberg Survey of gas prices says the cheapest gas in the country can be found in Tulsa, OK at $3.66 a gallon, while the highest is in Chicago at $4.45 a gallon.

Have high gas prices affected your driving habits this year?  Let us know in our poll!