PITTSBURGH — Frigid temperatures are keeping the Pittsburgh Zoo & PPG Aquarium closed through Friday.

The zoo had reopened Saturday after closing for six weeks for maintenance and construction of a new restaurant and an exhibit on endangered species.

Officials decided to close the zoo down again beginning Monday after the National Weather Service said temperatures wouldn’t climb above 23 degrees until Saturday.

Thursday’s high temperature is projected to be 9 degrees with a low of minus-6. The high will hit 36 degrees Saturday.