Unless you are doing a cloak for period costume, maybe you could use fleece?

Here is some cloak pattern information:

Here is a link that might be useful: Cloak Patterns

Nearly all of the pattern companies have cloaks..look in the costume section...I agree that fleece would be great to use for a cape and it is so easy to work with...

Is fleece REALLY warm? How about corduroy (spelling)?
Judy

Corduroy can be very heavy, especially if it gets wet. It is best used for shorter coats and jackets. Most patterns give you information on which fabrics should be used for each garment. Scroll down on the link for this info.

Here is a link that might be useful: cloak/cape pattern

Judy,
Yes, fleece really is warm. I made a fleece throw for our chilly TV room. I used two layers of fleece and serged them together. It's incredibly warm, not heavy and washable.

A couple of years ago I made a fleece cloak for my son (who is into SCA). He says it's nice and warm. Perhaps you could line the cloak with something lightweight?