If it's too cold to actually take your class outside, have them look at the view from a window. Then open the window and let them feel the cold air (make sure the window has a screen). Talk about how God made the seasons for us to enjoy.
If it's not too cold, bundle up your students and take them for a brief walk in the snow. Show them the different sizes of footprints as they walk. Observe the trees and bushes covered in snow (or peeking out from the snow). If it's snowing, have them stick out their tongues and catch snowflakes. Point out the each snowflake is unique or one-of-a-kind. Explain that God created each person to be special and unique (one-of-a-kind), too. Here's a picture of snow falling in Virginia:
Wherever you live, take advantage of your location to share God's creation with your students–even if it's through your photos. Take some time to thank God for His beautiful world each day.