(NewsNation) — Don’t look now, but gas prices are heading back up, and GasBuddy predicts the national average could hit $4 again in a couple of months. The price for a gallon of regular is up more than 13% nationally over the past month.

Some states have seen prices increase nearly a dollar per gallon this month alone.

Just six weeks ago, the national average was hovering at around $3 per gallon.

Since bottoming out, gas prices have steadily climbed. The current average is just shy of $3.50 per gallon, and no states are immune from the price hike.

Fifteen states now have averages above $3.50 per gallon, up from just six states last month. And now, not a single state is averaging under $3.10 per gallon.

Industry analysts say it’s not demand fueling the increase, but rather the winter weather.

“It all started in late December thanks to an arctic blast that hit much of the country, all the way down into Texas,” GasBuddy analyst Patrick De Haan told NewsNation affiliate WNCT. “The extremely cold weather caused equipment failures at refineries, so as a result gasoline production was disrupted.”

Warmer weather won’t necessarily mean lower gas prices, though. Prices typically rise in spring as refineries switch to summer-grade gasoline.

GasBuddy says that could mean a return to $4 per gallon gas as soon as March.

De Haan also cautions that a dip in demand is unlikely, even if Americans balk at the rising prices. He says easing COVID-19 policies in China mean more drivers there will be filling up and hitting the road.