You are planning to participate in a walkathon for a local charity. Which temperature would be most comfortable

It'd depend on humidity, if sunny or cloudy, etc. It also depends on you, and what temperatures you're used to! I'd personally say about 70 * F, but I don't know what temps you're used to! For some people, 70 is heavy-jacket weather, while for me it's short-shorts and t-shirt!