Can I still use washing machine when the weather is freezing outside? Is there a risk of pipes freezing while in use or pipes bursting? Should I only wash in the daytime?

Unless your washing machine is in a unheated garage or porch, I see no reason you can't use it. Need more information as to location of washing machine.

Yup! Need more info. Here. Why the concern? Where does the washing machine drain to (septic, city sewer, out to lawn)?

Are the water pipes on an exterior wall?

Back to you...

Mark