Hurricane Harvey is expected to hit the Texas Gulf Coast by Friday, with nearly one-third of U.S. refining capacity possibly in its path on the Texas and western Louisiana coastlines.
Winds of up to 75 mph and as much as 15 inches of rain were forecast, the National Weather Service said Thursday. That does not include the storm surge, which could bring even more water.
It could take 18 to 36 months for refineries to return to full production capacity if they sustain 2 feet of flooding, Bob Mitchell, president of the Bay Area Houston Economic Partnership, told CNBC's "Power Lunch" on Thursday.
However, the jury is out on whether oil refineries will sustain any flooding. That depends on the pace of the rain. Refineries could likely cope with 20 inches of rain over five days. They would have a tougher time keeping up if it rained 20 inches over 12 hours.
Houston-area refineries are responsible for significant portions of the nation's gas, military grade fuel and jet aviation fuel, Mitchell said. Any decrease in production could have ripple effects on manufacturing.
"Oh I will tell you it's worse than (a slowdown)," Mitchell said. "It's a shutdown, not a slowdown. I can assure you of that."
The issue is not local, it's national, Mitchell said.
— Reuters contributed to this story.