JPMorgan Chase & Co. Chief Executive Jamie Dimon said U.S. consumers still have some six to nine months of spending power left in their bank accounts but warned of an economic “hurricane” brewing.

The head of the nation’s biggest bank said the recent drop in Americans’ savings rate hadn’t altered his view that the government’s pandemic stimulus is still padding consumers’ wallets. He estimated that some $2 trillion in extra funds are still waiting to be spent.

“That fiscal stimulation is still in the pocketbooks of consumers. They are spending it,” he said at an investor conference Wednesday.

U.S. households boosted spending for a fourth straight month in April, but the rate at which they were setting aside savings fell to its lowest point in 14 years, according to data released last week. That raised concerns that consumers were tapping into savings to keep up with inflation and that the pandemic stimulus had run out.

Mr. Dimon said the data is heavily distorted by inflation impacts and shifting consumer-spending patterns in goods and services. Lower-income households aren’t quite as healthy, he added.

Bank of America Corp. CEO Brian Moynihan said Thursday his bank had seen spending continue to increase in May. He said that, except for gasoline, spending was exceeding price inflation—a sign that consumers aren’t slowing down.

“The spending is strong and then customers have more money in their accounts than they did prepandemic by multiples,” Mr. Moynihan said. “They’ve got plenty of money to spend.”

The executives both said the strong job market and higher wages will help bolster consumer spending along.

Mr. Dimon has been warning that the economy faces uncertainty, in part because unprecedented stimulus continues to play a role. He said Wednesday that there was an economic hurricane brewing.

For instance, he said, the war in Ukraine continues to roil commodity markets and could push oil prices above $150 a barrel. Brent crude traded around $117 a barrel on Thursday.

“That hurricane is right out there down the road coming our way,” Mr. Dimon said. “We just don’t know if it’s a minor one or superstorm Sandy. You have to brace yourself.”

Other bankers were more tempered. Mr. Moynihan said his customers still aren’t talking about recession fears. “We’re in North Carolina. You’ve got hurricanes that come every year,” he added. “So, we’re always prepared.”

Goldman Sachs Group Inc.’s President

John Waldron called the economic forces among the most complicated he has seen. But, he added, “I’m going to try not to use any weather analogies.”

Write to David Benoit at david.benoit@wsj.com