Basically, cold makes me "feel" tight. I think it makes me run "slower". But does it?
Process: I looked into my running log, picked all the Interval runs I had on Tuesday at my target running pace, and I calculated my %-age-of-target for each of these runs. (So if my interval pace was 9:00 and I ran the interval at 9:30 my percentage of target would be 94.7%) Then for each one of these runs I went into my log and pulled out the "feels like" temperature and did a scatter plot, tried to fit a trend line, and calculated a correlation.
Results: Although, the math says there is a correlation of 69.9% with those two sub 10°F temperatures (I was also going through a bit of gut cramping for those two-weeks), if we drop those numbers we see a weaker correlation on the remainder of 30.4%.
Conclusion: My running is basically unchanged in the range of 10°F-36°F. If there is a temperature function at work, it's slight, or I am able to adjust for it by altering my clothing for that day. It looks like the discomfort of running at these temperatures is really "all in my head".
I've been keeping a log of what I wear when I start my winter runs. And then I make a note of if I was cold at the start or at the end, or if I need to wear more or less if the conditions are the same next time. So far I think it's helped. For those two interval days running below 10°F (I have had 6 days below zero and 22 days below 10 total for this Winter's runs) I wore two pairs of track pants, a couple of technical shirts, a sweatshirt and a turtleneck with thermal socks, glove inserts and mittens!
Since I run a warm up distance before my interval running, this graph could also show me that my warm up is effective in bringing my body's working temperature to an efficient level for interval work.
At least this is just one less excuse for bad performance for me!