Montgomery County school leaders have expanded their request for a state waiver of instructional days lost to snowy weather, asking that a total of five school days be forgiven of the 180 days the state requires.

In a letter sent late Tuesday, Superintendent Joshua P. Starr mentioned the winter’s serious conditions and cited the cost of extending the school year: An extra five days, he said, would run $3.5 million to $4 million.

“This is in addition to the significantly higher costs we have experienced for our snow removal operations and for electricity and natural gas,” Starr wrote, just hours after the Maryland State Board of Education voted to allow state waivers for up to five days.

Montgomery County has closed its 202 schools for 10 days due to snow and ice this school year, but only had four emergency-weather days built into its calendar.

School leaders had hoped to take a combined approach to the shortfall: using the four days it had set aside; extending the school year by a day, to June 13; and requesting a state waiver for the remaining school days claimed by weather.

But Montgomery sought its state waiver on March 13, when nine snow days were on the books. It asked that four days be waived — only to be hit with another heavy snowfall, on March 17. Montgomery closed its schools again, which left a gap of five days

On Tuesday, the Maryland board voted to allow the state’s 24 school systems to apply for state waivers for one to five days and gave State Superintendent of Schools Lillian M. Lowery authority to decide waiver requests case-by-case.

Lowery said Tuesday she would act on requests quickly, but did not set a clear timeframe.

Montgomery schools spokesman Dana Tofig said Wednesday that the district would inform parents, students and staff as soon as possible of the state’s decision and the school system’s plan. “We know they are anxious to get this information, and we are anxious to give it to them,” he said.