Average gasoline prices in the U.S. are up for a fifth straight week, posting a 4.3 cent per gallon rise over the last week to $2.54 per gallon, according to GasBuddy data compiled from more than 10 million individual price reports covering 135,000 gas stations across the United States. The average price of diesel rose 0.4 cents to $3.01 per gallon.

“March madness is already in full swing at pumps across the country as the U.S. has seen the national average rise for five straight weeks and there’s no sign of a slowdown yet,” said Patrick DeHaan, head of petroleum analysis for GasBuddy. “Several perhaps major refinery issues flared up over the weekend, including fires at two facilities that could push wholesale gasoline prices up notably, mainly in the Pacific Northwest and the Gulf Coast, should the shutdowns linger. This is the time of year that energy markets are very sensitive to such unexpected outages as dozens of refineries across the country perform maintenance in a tight window ahead of the summer driving season. Any major outages can lead to tight inventory ahead of specification changes and have a severe impact on gas prices. The situation is delicate and bears further monitoring in the days ahead.”

The price of West Texas Intermediate crude oil was up 14 cents per barrel to $58.66, a rise of nearly $2.50 per barrel from a week ago as oil inventories fell nearly 4 million barrels last week, according to the EIA. Brent crude oil meanwhile, was up 19 cents to $67.35 per barrel in early trading Monday morning.

In last week’s report from the Energy Information Administration, oil inventories stood 18 million barrels above their year ago level after falling 3.9 million barrels from the previous week. Gasoline inventories fell 4.6 million barrels and remained just ahead of year-ago levels as not a single region saw a rise in gasoline stockpiles as refiners continued maintenance. Refinery utilization increased slightly, rising 0.1% to 87.6% while both gasoline and distillate production fell. The East Coast utilization rate jumped 4.1% while the Midwest saw a 0.4% improvement. The Gulf Coast, Rocky Mountains and West Coast regions all saw utilizations fall.

At gas pumps, motorists saw another bump up in price in most areas. 48 of the nation’s 50 states saw a weekly gain while just Ohio and Indiana saw prices fall- but that fall will be short-lived as prices will likely spike this week in those two holdouts. South Carolina re-claimed the title of cheapest gasoline in the country with average prices at $2.29 per gallon, followed by Wyoming and Arkansas at $2.30 per gallon. California kept the title of nation’s priciest gallon with an average of $3.34, followed by Hawaii at $3.26 and Washington at $2.96.

Several refinery issues arose over the weekend, mainly in the West Coast, that could cause gas prices to either continue moving up gently, or soar. Phillips 66 saw a fire at its Carson, CA refinery while Chevron reported a flaring event at its Richmond, CA facility. In addition, BP’s refinery in Washington state was going down for planned maintenance just as Shell’s Anacortes refinery was, leaving the Pacific Northwest likely susceptible to price shocks from unplanned outages. In addition, ExxonMobil reported shutdown of a gasoline producing unit at its large Baytown, TX refinery. While as of press time it is too early to fully know where gas prices may go as a result, there will likely be some impact in the days ahead.

Gas prices are likely to rise again this week, leading to a sixth straight week of advances as seasonal maintenance is ongoing and as the transition to summer gasoline continues into its third week across much of the country.

For budget-minded drivers, GasBuddy is the travel and navigation app that is used by more North American drivers to save money on gas than any other. Unlike fuel retailer apps, as well as newer apps focused on fuel savings, GasBuddy covers 150,000+ gas stations in North America, giving drivers 27 ways to save on fuel. That’s why GasBuddy has been downloaded nearly 90 million times – more than any other travel and navigation app focused on gas savings.