The cold temperatures combined with Saturday's snowfall have ski resorts bustling.
Bear Creek Mountain Resort in Macungie opened the slopes to skiers and snow boarders on Sunday.
Officials said four slopes were up and running on the mountain.
They said the cold temperatures allowed them to blow snow and get the trails ready for opening day.
"It's so wonderful to see the slopes full, the snow guns on and the sun shining. It's just such a wonderful feeling to have people here and know that they're having fun," said Megan Diehl, marketing manager at Bear Creek.
The resort is also ready to ring in the New Year on Monday with a free party.
And skiers and snow boarders can enjoy themselves on the mountain until 1 a.m. on Tuesday.