The first thing you need to do is create a legend. You can follow mine, but it might not be a good fit if you live in a warmer climate, or even another part of Canada. I would suggest making your own legend, or following one from Pinterest if you aren't into math.
First you need to choose the number of colours that you want to use (I used 9). I recommend using multiple shades of the same colour, and throwing in some neutral shades as well. I have seen some that are rainbow colours, but they are a little bright for me. I used reds, blues, and browns.
Next, you need to get a sense of what the range of temperatures will be for your location. If you go to the weather network you can find their monthly forecast page that will give you past weather data.
If you are in Canada, you can also look at this Government of Canada website to get an idea.
For my legend, I had -45'C as the extreme cold temperature, and 35'C as the extreme high temperature. I wanted the colour to change at 0' so I modified things that way. I only ended up having 1 day of -37 and colder, and I ended up having a couple days of +37 that I hadn't included in my legend, so I re-used another colour.
Take the extreme temperatures and subtract them to get the total number of degrees in your range.
E.g. 35 - (-45) = 80
Then divide that number by the number of colours you want to use.
E.g. 80 / 9 = 8 (ish)
Then make your legend, using a range of that number of degrees (8) for each colour. I also decided to add a second strand of lighter white yarn on days that it snowed. Here is how my legend turned out:
You should buy 2 balls of each colour, just in case. I only bought one ball of each colour, but ended up running out of a few colours. Unfortunately Michael's had discontinued the exact colour that I needed so I had to find a replacement. It ended up not being very noticeable because you are changing colours so often.
I recommend making a chart where you can write down the temperature/colour for each day and check it off. If you're anything like me, you may not be able to knit every single day and may need to do some catching up. I just had a little notebook and made a chart by hand.
I used the exact temperatures from the website above, and knit the row a day behind. I used the measured temperatures, not the windchill or humidex temperatures. I used the following temperatures:
Fall: Daily Average
Winter: Daily Low
Spring: Daily Average
Summer: Daily High
Now you're ready to knit! Here's how:
Materials:
6mm (US 10) circular needle
Approximately 18 balls of worsted weight yarn (I used Impeccable from Michael's) Note: you will have yarn leftover, but buy at least 2 balls per colour
Directions:
Cast on 167 stitches
Knit garter stitch (knit every row) across. Knit one row per day for a total of 365 rows.
Cast off and sew in all the ends.
Finished size is approximately 46" x 64".
