Hawaii's two refineries continued operating on Friday as Tropical Storm Iselle made landfall on the archipelago's Big Island, the companies said.
The refineries on the island of Oahu, about 187 miles (300 km) northwest of the Big Island, were monitoring weather conditions and taking precautions.
"We are continuing to operate the refinery at moderate throughput," said Lance Tanaka, spokesman for Par Petroleum Corp's 94,000 barrel-per-day (bpd) refinery in Kapolei near Honolulu, the larger of the two plants.
Chevron Corp said it would adjust operations at its 54,000-bpd Honolulu plant accordingly if necessary.
Iselle weakened into a tropical storm before it reached the islands, but Hurricane Julio on Iselle's heels was expected to reach the area as early as Sunday.
However, prediction models showed Julio weakening before then on a track about 150 miles (240 km) north of the islands, according to the National Hurricane Center.
Tanaka said Par Petroleum expected heavy rain on Oahu, and the company intended to keep the refinery running unless conditions worsened.
(Reporting by Kristen Hays in Houston; Editing by Lisa Shumaker)