Retail sales were lifted in September by spending and higher prices.

Retail sales rose unexpectedly in September, as American consumers shook off fast-rising prices, shortages of goods, and the Delta variant outbreak in many parts of the country.

It was the second straight month of gains. Sales climbed 0.7 percent in September, following a 0.9 percent gain in August, the Commerce Department reported. The increase in spending was broad-based, with sales at restaurants and bars, clothing stores and home goods stores climbing.

The sales data measures dollars spent at businesses in the United States, so the increase partly reflects inflation in the cost of everyday products from food to gasoline. Consumer prices are increasing at the fastest pace in years, a phenomenon largely attributed to the uneven reopening of the global economy.

But the broad takeaway from Friday’s report was that consumers — the key driver of U.S. economic activity — remain willing to spend for now, economists said. Analysts had expected sales to decline about 0.2 percent, according to a survey conducted by Bloomberg.

“People believe that they have learned to manage the virus,” said Beth Ann Bovino, chief U.S. economist at S&P Global. “Many are vaccinated, and they’re tired of staying at home and want to go out and spend.”

That urge could continue, Ms. Bovino said, as the Delta variant ebbs. New infections in the United States are down more than 40 percent since August, and hospitalizations and deaths are declining.

Though monthly retail sales spending is now higher than it was before the pandemic, the data has been uneven lately. The fact that September’s data was a second month of gains — with August’s reading revised higher — was also a good sign, said Gregory Daco, chief U.S. economist at Oxford Economics.

“While the month-over-month numbers have changed, what really matters is the trajectory of consumer spending,” he said. “An improving health situation should spur renewed consumer optimism while a resilient jobs recovery should support income growth.”

Spending at clothing stores rose 1.1 percent in September, while sales at sporting goods, hobby, musical instrument and book stores were up by 3.7 percent. General merchandise stores, such as department stores, also saw an increase of about 2 percent.

Still, there were some reasons to be cautious about Friday’s report. For one, sales in some key categories did most likely reflect higher prices rather than increased demand.

Auto sales rose 0.5 percent in September, for example, despite a shortage in semiconductors and shipment delays that has hampered new car sales. The Bureau of Economic Analysis reported earlier that unit sales of automobiles were down 6.2 percent in September.

Rising fuel costs also likely lifted the sales total. Oil prices have climbed to their highest level in seven years recently amid a global energy crunch, and sales at gas stations rose 1.8 percent in September. “Since it’s the end of the travel season, I believe the increase at gas stations was driven by an increase in prices at the pump,” Ms. Bovino said.

Analysts at Bank of America, citing credit card data gathered by the bank, said on Friday that the increase in spending on gasoline, lodging, airfares and at grocery stores can largely be attributed to inflation.

The analysts wrote in a research note, however, that “all of the other major categories have seen real growth.”

The increase in prices could still become a drag on the economy. With prices still rising at a year-over-year pace of more than 5 percent, in part because of persistent supply chain disruptions caused by the pandemic, surveys of consumer sentiment show it is deteriorating, and that could presage a slump in spending.

The Conference Board’s Consumer Confidence Survey fell in September for the third consecutive month, and preliminary results from the University of Michigan’s monthly consumer sentiment survey, released Friday, also showed confidence dropped 1.9 percent, to 71.4, in early October. That’s the lowest reading since 2011.

To relieve some supply chain issues, President Biden announced Wednesday that the Port of Los Angeles would double its hours of operation, and major companies including Walmart, UPS and FedEx will expand their working hours in hopes of addressing backlogs. The moves come ahead of the holiday season and are intended to resolve a logjam that has slowed the shipment of manufactured goods from Asia.

The shortages could begin to hamper holiday sales — or prompt consumers to spend early to stay ahead of the bottlenecks, Ms. Bovino said.

“People are willing to spend, it’s just a question if they can find the items,”she said.