Hawaiian Electric Co. customers saw some relief in October with the month’s average electric bill declining more than $3 amid a drop in oil prices.

The bill for a typical household using 500 kilowatt-hours on Oahu is $130.77 this month, $3.21 lower than what customers paid in September, when it was $133.98.

HECO spokesman Darren Pai said bills decreased due to lower fuel costs.

The price of benchmark West Texas Intermediate crude oil dropped to $40 in the beginning of August from $50 a barrel in July. The price has climbed back up in October, and closed at $50.18 a barrel on Wednesday.

October’s good news is the second decrease in electrical bills for Oahu after three consecutive months of rising prices. Despite the lower prices, Oahu residents are still paying more than they did in May before a three-month trend of rising fuel costs.

The bill for a typical household on Oahu in September was 75 cents lower than in August. August was $1.30 higher than in July. For the month of July, the electric bill was $4.09 higher than what customers paid in June. Oahu’s June bill was $4.49 higher than what customers paid in May, when the typical household bill was $124.85.

HAWAII has the highest electricity rates in the United States, primarily due to the state’s use of imported oil for most of its power.

In 2015 oil made up roughly 71.1 percent of HECO’s energy mix on Oahu. It made up roughly 62.5 percent of the energy mix at Hawaii Electric Light Co. on the Big Island and 73 percent of the energy mix at Maui Electric Co. HECO imports oil mainly from Southeast Asia and the Middle East. Other states use energy resources such as natural gas, hydroelectric power, coal or nuclear power.

The price of electricity in the state is nearly double the national average, according to the latest figures from the U.S. Energy Information Administration. Hawaii residents paid an average of 28.04 cents a kilowatt-hour in July; the national average was 12.68 cents in the same month.

Residents on neighbor islands also saw a discount in October from the previous month.

The residential rate for HELCO customers on Hawaii island was 29.7 cents a kilowatt-hour. The average bill this month for a household using 500 kilowatt-hours on the Big Island is $159.97, down from $161.85.

Maui customers paid 26.9 cents per kilowatt-hour, down from 27.2 cents in September. The average bill for a household using 500 kilowatt-hours is $143.94, down from$145.42, last month.

Maui Electric Co. customers on Molokai using 400 kilowatt-hours of electricity are paying an average of $128.21, with a rate of 29.6 cents a kilowatt-hour, down from September, when the typical bill was $133.35.

ON LANAI bills were down. Those using 400 kilowatt-hours of electricity on Lanai are paying 31.6 cents a kilowatt-hour. Lanai residents are paying $136.08 in October, compared with $136.43 in September.

The typical customer bill on Lanai and Molokai is measured with electrical use at 400 kilowatt-hours due to lower energy use, HECO said.

HECO, MECO and HELCO monthly bills include the cost for kilowatt-hours used plus other charges.

The Kauai Island Utility Cooperative increased its rate to 32.71 cents a kilowatt-hour in October, up from 31.95 cents in September. The average bill for a household using 500 kilowatt-hours of electricity, including a $10.58 customer base charge, is $174.14, up from $170.33.