CHICAGO (CBS) — Hurricane Harvey has already had an impact on gas prices, and it’s expected to continue having an impact for weeks to come.

With refineries offline in Houston, Patrick DeHaan, Senior Petroleum Analyst at GasBuddy, says we could see prices in the $2.60 to $2.70 range possibly by Tuesday afternoon, which would be the highest we’ve seen in about two years.

DeHaan says this is a real cause and effect situation, not just speculation, as about 15 percent of the nation’s refining capacity is shutdown.

The good news, he says, is refineries that shut down in Corpus Cristi as a precaution ahead of the storm are getting back to production and will likely make up for some of the lost refining capacity.

How long we’ll see higher prices, he says, really just depends on how long refineries are down.

Demand typically drops after Labor Day and prices will drop in the Midwest as more expensive summer-blend gasoline is phased out.