I have a very simple guide to figuring out what to wear when running outside. I take the current temperature in Fahrenheit and add 20 degrees to it. I wear what would feel comfortable if I was standing still at 20 degrees warmer. Usually, that works pretty well.
Yesterday, I stumbled across a very cool guideline by Runner's World on the internet for figuring out what to wear that not only takes into consideration the temp, but the wind and rain as well. Here's the link.
Out of curiosity, after I finished today's run, I checked to see what Runner's World would have recommended. It was about 45 degrees when I started my run, breezy and sunny. I had worn shorts, a long sleeved technical shirt, a visor and sunglasses. My hands were cold when I started and I pulled down my sleeves to cover them during the first half mile or so. Runner's World suggested that I wear what I had chosen plus a mesh vest and lightweight gloves that I could tuck in my shorts waistband if I got hot. I had considered wearing a windbreaker vest this morning and I briefly wished that I had my gloves when I started. Both would have made me more comfortable particularly during my first mile. The vest I was considering wearing would have been too hot after I got warmed up, but I also have a mesh vest that would have worked great....I just didn't think of it.
I think I'll try to check Runner's World recommendations more often as the weather changes. It will help make my runs more comfortable.