Gas prices on the move before Memorial Day

Updated May 25 at 9:57 ET

Gas prices have been on a downhill slide since early April -- good news for the nearly 35 million Americans expected to drive somewhere nice for Memorial Day. And experts' predictions that prices would fall even more as the long holiday weekend arrived were mostly correct.

But just when you thought it was safe to get back into road-trip mode, gas prices shot up in some locations. For instance, a radio station reported an overnight 20-cent spike at some Louisville, Ky., gas stations earlier this week.  (Post continues after video.)

In Clark County, Ohio, "many stations listed gas for $3.59 a gallon Tuesday morning. By 3 p.m., several stations had jumped to $3.79 a gallon," the Springfield News-Sun reported. A GasBuddy analyst said Ohio's average price jumped 6 cents in 24 hours. 

Meanwhile, the West Coast continues to get slammed by prices well above the $4 mark, due to refinery shutdowns. "Analysts on Wednesday warned that gas prices in the state could spike by as much as 35 cents before the weekend is over," The Bellingham Herald in Washington said.

Elsewhere around the nation, the price of regular continued to fall. Overall, the national average Friday is $3.666, 17.4 cents lower than a month ago.

Here's what's going on in other states, via the AAA Fuel Gauge Report:

• In Pennsylvania, the Friday average is $3.636, down from $3.645 the day before and $3.907 a month ago. The year-ago average was $3.838, making holiday travel this year a relative bargain.
• In New Jersey, Friday's average is $3.574, down 5.2 cents from the week before. 
• Colorado's average is $3.755, compared with $3.884 a month ago.
• Here in Montana, where cold and wet are predicted for much of the state, the average is $3.780, a bit higher than $3.773 a week ago and $3.774 last month.

AAA reported an average in Oregon of $4.221 on Friday, nearly a cent higher than the day before and way above last month's $4.041. In Washington, the average price is $4.242, 0.4 cent higher than Thursday. Compare that with $4.098 last month.

California gasoline is even more expensive, with a $4.302 per gallon average, but better than $4.360 a week ago.

The lowest average is in South Carolina, where Spoleto Festival USA begins this weekend -- at $3.299, compared with $3.388 the week before. 

The nationwide average is 14.8 cents lower than it was this time last year -- good news because Memorial Day is a driving holiday. AAA says 88% of those who have travel plans will be behind the wheel.

It predicts that 34.8 million Americans, about 500,000 more than a year ago, will drive at least 50 miles away from home. The average total distance traveled will be 642 miles, 150 fewer than last year. The Washington Post adds, "The biggest increase in planned travel is among those making more than $100,000."

Why have gas prices been dropping? There's plenty of supply (except on the West Coast) and lower demand. Also, says The Associated Press:

Worries about Iran interrupting oil supplies from the Middle East have eased, the Chinese economy which had sent demand up has cooled a bit and challenges to the Euro and concern about European debt has also eased speculation in oil futures.

Despite what you may believe, experts say gas prices have dropped ahead of Memorial Day for three years in a row. 

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". . . it's time to put to bed an old myth that gasoline prices rise ahead of a major holiday," Patrick DeHaan, senior petroleum analyst for GasBuddy, said earlier this week. "Average gasoline prices will likely continue to decline in the days ahead of Memorial Day."

Do you have travel plans for Memorial Day? How have gas prices figured into them?

More on MSN Money:

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