I am using a garter stitch chevron pattern from 200 Ripple Stitches. (Weird prejudice: ripples are for crochet and chevrons are for knitting, surely!) I got this book from the library in an attempt to seduce Elaine into crocheting something other than straight lines, but I don't think she has had a chance to even look at it yet.
I started on 4.5 mm needles, but after a few days decided the fabric was too stiff, so changed to 5s, after carefully noting on 2015's calendar to go back to 4.5s a few days before the winter solstice, to make things symmetrical!
I get my data from here; at the bottom of the page it gives you yesterday's high and low temperatures. So since I started knitting on Dec 21, the first date represented is Dec 20. (The colour code is in this post; I use one yarn for the high temperature and one for the low. You can see in the middle there were a couple of days where it didn't get much colder at night and I used two strands of plain green.)
The Koigu is beautiful yarn; I'm quite looking forward to my one little garter ridge each day!