Average gas prices in Honolulu dipped below $4 a gallon Thursday for the first time since March and appear headed to their lowest level in nearly four years.

Honolulu prices could fall to $3.60 by mid-January, said Tom Kloza, chief oil analyst for New Jersey-based Oil Price Information Service. Already some Oahu gas stations are selling regular for less than $3.80.

"Hawaii will see some average prices it hasn’t seen since the winter of 2010 in the next 90 days," Kloza said.

A sudden plunge in the global price of oil, which closed at $84.47 a barrel Thursday, should benefit Hawaii consumers in a variety of ways, including lower gas prices, shipping costs, electrical bills and airline tickets.

"Whether you’re in Paris, Texas, or Paris, France, you should be seeing lower fuel prices not only for gas, but for diesel and jet fuel, too," Kloza said. "Since around June 25 the global price of fuel has dropped by about $30 a barrel, or about 70 cents a gallon."

The decline is being felt around the country with the U.S. average for gas at $3.16 a gallon.

"If this drop stays where it is, that would effectively be a $600 tax credit to an average American household," says Ed Morse, global head of commodities research at Citigroup.

The average price in Honolulu on Thursday was $3.998. The last time Honolulu’s average gas price fell below $4 was on March 2 when it hit $3.994. The last time Honolulu reached $3.60 was in late January 2011.

Motorists on Oahu can now find gas prices as low as $3.71 at a Tesoro station in Nanakuli, while a Tesoro station on Kapahulu Avenue is offering gas for $3.77 on a cash-only basis, according to GasBuddy.com.

A week ago the average price for regular gas in Honolulu was $4.055, and a month ago it was $4.211.

Honolulu typically trends lower than the state. As of Thursday, Hawaii was the only state with an average gas price above $4. The statewide average was $4.108.

Hawaii has another 10 or 20 cents of catching up with the downward global trend, said Kloza.

"There’s certainly enough room for refiners and retailers to be profitable with prices under $4," he said. "I think in Hawaii’s case it (goes below $4 statewide) this month."

Matson Co. said it has been monitoring bunker fuel prices as it typically does but didn’t indicate whether it soon would be lowering its fuel surcharge.

The state’s largest ocean shipper decreased its fuel surcharges three times in 2013 — by a combined total of 9 percentage points — to 34.5 percent before increasing its surcharges twice in 2014. The last increase of 3 percentage points in June raised the fee to 42.5 percent.

"Gas and bunker fuel (which ships burn) are different, so they don’t always mirror each other," Matson spokesman Jeff Hull said. "We do monitor these things, and when we have downward trends in bunker fuel and the type of fuel we burn, we have been pretty quick in bringing down prices, and we can make it effective immediately."

In 2008, Hull noted, Matson dropped its fuel surcharge six consecutive times by a total of 27 percentage points to 15 percent.

Hawaiian Airlines, which spent $174.1 million on fuel costs in the second quarter and $345.3 million during the first half of the year, declined to comment Thursday on the recent effect of jet fuel prices on its business because the company is issuing its third-quarter earnings report Tuesday. However, Hawaiian and other airlines often have said that rising fuel costs were the catalyst for them charging fees for checked bags beginning for some in 2008.

"Airlines have gotten a nice break recently on jet fuel prices," Kloza said. "We’ll have to see whether it translates to lower airfares."

Hawaiian Electric Co., the state’s dominant utility provider, said more than half of a household’s typical monthly electrical bill pays for fuel and power that HECO purchases from independent renewable and conventional power producers. HECO said changes in the monthly bills it charges consumers almost always reflect a change in fuel prices. This month the bill for a typical household on Oahu using 600 kilowatt-hours will be $213.91, down more than $5 from the previous month.

The global price of oil is down about $31 a barrel, or 27 percent, from its high point for the year. That means the world’s oil-producing countries and companies are bringing in as much as $2.8 billion less in revenue every day — and consumers, shippers and airlines are saving a comparable amount on gasoline, diesel and jet fuel.

The global price of oil was relatively stable for nearly four years, averaging $110 per barrel. Increased production in the U.S., Canada, Iraq and elsewhere made up for declining supplies in nations such as Iran and Libya and helped meet rising global demand.

That delicate balance has been upended by a weaker global economy. Demand is slowing while production, particularly in the U.S., continues to surge.

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Hawaii is the only state with regular gasoline averaging $4 a gallon or higher. The top 10 highest average prices in the nation:

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