About a third of museums surveyed in the United States were operating in the red or close to it before coronavirus, Ms. Lott added; three-quarters have now closed and one-third will not reopen if the crisis continues. “This situation is by far more dire than anything I have experienced in my 25 years of being an arts finance professional,” she said.

The Tenement Museum on Manhattan’s Lower East Side — which has a $2.7 million cash endowment and depends on earned revenue for over 75 percent of its operating costs — has laid off 13 employees, which amounts to a 20 percent reduction in staff.

“Our budget projections now take us through the end of June showing no revenue,” said Morris Vogel, the museum’s president, adding that the institution owes about $9.5 million in bonds with covenants that restrict its ability to borrow money. “We still have to make those monthly payments.”

The Met, preparing for its own financial hardship, has developed a three-phase response: having all staff members work from home and continue to be paid through April 4 as the museum evaluates possible furloughs, layoffs and voluntary retirements; from April to July, evaluating how to control spending and reduce operating costs, including freezing discretionary expenditures and hiring; and from July to October, “reopening with a reduced program and lower cost structure that anticipates lower attendance for at least the next year due to reduced global and domestic tourism and spending,” according to the letter.