Hawaiian Electric announced Thursday that many customers can soon expect a decrease in their monthly energy costs due to oil prices falling worldwide.

This applies to customers on the Big Island, Maui, Molokai and Lanai. Oahu is projected to experience an increase, but this was already expected due to the scheduled closing of the island’s last coal plant. Now, the increase is projected to be lower.

Oahu customers were expected to pay an extra 7%, or $15 on average, but now their bills are projected to be an extra 4%, or $9.

Russia’s invasion of Ukraine in late February scrambled global energy markets, sending the price of crude oil to over $120 per barrel. This was a significant increase from December’s price of around $70 per barrel, and energy costs reflected that — here in Hawaii, the average gallon of gas went from $4.08 a year ago to a high of $5.62 this past July.

But the price of oil changes often.

According to a CNBC analysis, higher oil prices have ordained lower energy demand, and that plus the fear of a possible recession — when demand would be even lower — has contributed to oil’s lower prices. The analysis also points to President Joe Biden’s decision to tap the Strategic Petroleum Reserves — which increases supply — in its explanation for oil’s current decline.

For now, this means many HECO customers can expect lower costs this September, which will be visible when they’re billed in October.

Projections show that a typical customer on Molokai will save 14%, or about $34 on average. By the same metric, Lanai customers will save 9%, or $22; Big Island customers will save 6%, or $16; and Maui residents will save 5%, or $11.

These numbers vary island-to-island based on factors like customer count and available energy mixes, said spokesperson Shayna Decker.

Costs will still be higher than they were back in March, before the surge.