BOSTON — Gov. Charlie Baker formally asked the federal government Friday to declare a disaster in 10 Massachusetts counties after a relentless series of winter storms brought record snowfall and frigid temperatures, causing 25 deaths and costing the state and its cities and towns an estimated $400 million.

The request was made in a 22-page letter to President Obama, delivered through the acting regional administrator of the Federal Emergency Management Agency.

Citing an “unprecedented and disastrous pattern of severe winter weather,” the letter seeks 75 percent federal reimbursement for snow removal and other costs related to the storms, which Baker is asking FEMA and the president to treat as a single, monthlong disaster.

“Despite our experience in dealing with harsh winter conditions, this severe pattern brought (Massachusetts) to a virtual standstill for days at a time,” Baker wrote. “Our public transit system collapsed, and private sector commerce, government services and healthcare suffered severe disruptions.”

While his administration took a number of steps to respond, the impacts went beyond the state’s capabilities and prompted appeals for snow removal equipment and personnel from states as far as New Jersey and Pennsylvania, Baker said.

As of March 15, Boston had received 108.6 inches of snow – about 9 feet – topping a seasonal record of 107.9 inches that was set in 1995-96. Nearly 65 inches fell in February alone, shattering the previous one-month record of 43.3 inches in January 2005.