When it gets cold we tend do get dry, especially from running the heat in the house or at work from being cold. This is a great time to love up on your hair by gently handling it, doing long deep conditioning, using leave in conditioners as well as coating the hair with essential oils or serums. The hair can be so delicate and fragile sometimes. Hair requires for us to pay attention to it and to nourish the hair with things only we know it needs, because it can't nourish itself. So its good to be educated, at least to the point that you have discovered what your particular hair type needs and wants. If the hair is feeling dry and brittle; then it is probably needing more moisture.
Ways to keep the hair moisturized during this time are allowing the conditioner to sit longer on the hair. 30 minutes is a good time for the conditioning agents to go in deep in the hair and penetrate. Also using more thick cream based leave in conditioners that will add lots of protection to the hair while in to outside elements will be a big benefit. Also when styling the hair, it would not hurt to add a little more oil for locking in moisture and protecting the hair strands or using thicker styling pomades and/or creams that will create a barrier around the strand giving it protection and increasing elasticity in the hair. If your hair is worn short, relaxed, natural or curly; the heavy leave-ins and styling agents will be great.
Use a good serum on the hair for styling and thermal protection that has things in it that will help build the hair up such as simple amino acids or silicon in it. This will protect the hair without compromising the movement in the hair. Be sure to wrap the hair at night with silk or satin to keep the ends smooth and protected as well.