The yarn for this pattern is not available at Destination Yarn just yet - it is currently only at Joseph Beth Booksellers in kits that include this pattern, needles, and yarn. However the info for the yarn is this:

100% Merino Wool
215 yards / 3.5 oz / 100 grams
Worsted Weight
4-5 stitches = 1” on #7-9 needles
Machine wash cold, lay flat to dry

The Scarf and base of the hat take 1 skein with about 75 yards of a coordinating yarn needed to finish the hat.

Happy Knitting!