Snow, sleet and ice Sunday, followed by frigid temperatures, have many schools canceling classes Monday — and in some cases Tuesday.

Some observers warn that schools could be closed all week.

[Live updates: Winter Storm Fern’s icy aftermath]

A handful of districts, including Howard, Charles, Queen Anne’s and Wicomico counties, were already out of school Monday for reasons unrelated to the weather.

Many colleges and universities have canceled in-person classes or announced closures.

Here is a list of K-12 school closures.

Allegany County Public Schools will close Monday. | Read the alert.

Anne Arundel County Public Schools will close Monday. | Read the alert.

Baltimore City Public Schools will close Monday. | Read the alert.

Baltimore County Public Schools will close Monday and Tuesday. | Read the alert.

Calvert County Public Schools will close Monday. | Read the alert.

Caroline County Public Schools will close Monday. | Read the alert.

Carroll County Public Schools will close Monday. | Read the alert.

Cecil County Public Schools will close Monday. | Read the alert.

Dorchester County Public Schools will close Monday. | Read the alert.

Frederick County Public Schools will close Monday. | Read the alert.

Garrett County Public Schools will host a virtual learning day Monday morning. A three-hour early student dismissal was already in place for teachers’ professional development. | Read the alert.

Harford County Public Schools will close Monday and Tuesday. | Read the alert.

Howard County Public School System will close Tuesday due to inclement weather. Schools were already closed Monday for unrelated reasons. | Read the alert.

Kent County Public Schools will close Monday. | Read the alert.

Montgomery County Public Schools will close Monday and Tuesday. | Read the alert.

Prince George’s County Public Schools will close Monday. | Read the alert.

Somerset County Public Schools will be virtual Monday. | Read the alert.

St. Mary’s County Public Schools will close Monday. | Read the alert.

Talbot County Public Schools will close Monday. | Read the alert.

Washington County Public Schools will close Monday and Tuesday. | Read the alert.

Worcester County Public Schools will close Monday. | Read the alert.