Julia Kelleher, Puerto Rico's secretary of education, told CNN on Sunday that some public schools might not resume classes until October 16 because of storm damage, though decisions will be made on a regional basis.
There are 1,113 public schools and a student population of 350,000 on the island but only 400 schools have been assessed for damage, she said.
"I have come up with a target date of October 16th," Kelleher said. "We used to make system-wide decisions before, but this time we're going to allow the different regions to make their own decision as to when they can reopen."
Schools started classes August 14 but students have already missed two weeks because of Hurricane Irma, which lashed the island only days before Maria hit.
The report on schools came one day after President Trump took to Twitter to criticize the leadership of island officials, especially the mayor of San Juan.
Trump, who plans to visit the island Tuesday, criticized San Juan Mayor Carmen Yulín Cruz
and the "leadership ability" of some in Puerto Rico who "want everything to be done for them when it should be a community effort."
Cruz earlier had criticized the distribution of aid to the island and said federal authorities needed to do more. In addition to widespread power outages, many people have limited access to gas, cash and running water.
FEMA said Sunday it has expanded its delivery of food and water throughout Puerto Rico, though officials stressed that many people still lack the essentials.
The federal emergency agency has delivered food and water to all 79 municipalities in Puerto Rico, Alejandro De La Campa, FEMA federal coordinating officer in Puerto Rico, told reporters Sunday. He said 1 million liters of water and 1 million meals had been delivered as of Saturday.
However, he said some isolated areas of these municipalities may not have received the commodities, partly because lack of communication systems has hampered distribution efforts.
Officials provided an update Sunday morning on recovery efforts and the island's infrastructure:
Water. 41% of the island has potable water.
Food and water delivery. Eleven regional staging areas are open for food and water distribution but officials hope that number will grow to 25 in coming days. About half the grocery stores are operating.
Electricity. 5% of the island has power. The Army Corps of Engineers has begun a mission to repair the power grid, Puerto Rico Gov. Ricardo Rossello said.
Gasoline. More than 710 of the island's roughly 1,110 gas stations were working as of Saturday morning, but lines were long and some stations were closing ahead of the 9 p.m. curfew.
Fuel delivery. Over the next few days, close to a million gallons of gasoline and half a million gallons of diesel fuel will arrive, the governor said. As of Sunday, 470,000 barrels of gasoline were in Puerto Rico.
Communications. 36% of people now have phone service in Puerto Rico, most in the northeast part of the island. All the island's landlines are operating but only about 11% of the cell towers are operational.
Shelters: 8,800 people remain in 139 shelters. Rossello saw this as an improvement because 500 shelters were operating 10 days ago.
Air travel. 39 passenger flights were expected on Sunday in Puerto Rico, which has a maximum efficiency of 60 flights.
Medical care. 51 of 69 hospitals are running in some capacity now, along with 46 of 48 dialysis centers.
Islanders receiving benefits under Puerto Rico's Nutrition Assistance program who have been displaced by the hurricanes can apply for benefits under the Supplemental Nutrition Assistance Program (SNAP), the USDA announced Sunday. The policy will remain in effect through October 31.
Hurricane Maria struck as a category 4 storm on September 20. At least 16 people on the US commonwealth died, the government has said.