Gasoline prices are 'highest ever for this time of year': Chart of the Day

Gasoline has never cost this much in September, while diesel prices touched a new record on Wednesday as crude oil topped $100 a barrel.

"Gasoline prices in the USA are the highest ever for this time of year," Andy Lipow of Lipow Oil Associates said.

While Brent crude ( BZ=F ) has edged past $100 for the first time in two months , the pain at the pump is even greater. Energy bottlenecks and refining constraints tied to the US-Iran conflict have pushed crack spreads — the gap between crude and refined fuel prices — to new highs.

Consumers are effectively paying the equivalent of $177 a barrel for gasoline and $250 a barrel for diesel, according to Lipow's analysis.

"Those high prices are starting to impact demand," he said.

Gasoline and diesel futures show a year-to-date surge of more than 78% and 124%, respectively, according to AlphaSpace data.

The national average for regular gasoline stood at $4.22 a gallon on Wednesday, more than $1 higher than the same time last year, according to AAA data .

Though prices have eased off their peak north of $4.50 in May, they currently "remain at record levels on a seasonally adjusted basis," JPMorgan analysts wrote on Wednesday.

"American drivers paid the highest gasoline prices on record during the Labor Day weekend," the analysts noted.

The national average for diesel stood at $5.94 per gallon on Wednesday, with futures suggesting the benchmark is poised to hit $6 in the coming days. The surge is expected to drive up the cost of goods and services, given how heavily diesel is relied upon for farming, trucking, and deliveries.

On the West Coast, where taxes are high and refining capacity is limited, the impact is even greater. California diesel is on the cusp of $8 a gallon, with some cities averaging nearly $8.50, according to GasBuddy head petroleum analyst Patrick De Haan.

"Keep in mind, California's a huge agricultural state," he said. "So, to see those apocalyptic diesel prices in California, I mean, we're talking about some stations that may have to figure out software updates for potentially double-digit diesel prices."

Ines Ferre is a Senior Business Reporter for Yahoo Finance covering the US stock market, publicly traded companies, and commodities.