Wishing it were colder in Feburary?

Today was day 2 of week 3, and it felt harder than day 1! This is the first time that happened so far. I blame it on the weather.
My very first day running it was in the high 40s so I wore a sweatshirt and a light jacket, and I about died of heat exhaustion. I've always been the only cold person in a room full of people so that was pretty shocking to me. Since then I've under dressed to run and been much more comfortable. But today I just wore a t-shirt and a really light jacket and it was still too hot. It's 64 degrees outside! This is the first time in my entire life I was wishing it was in the 40s.
My calves felt weird today too, I think it's what people mean when they say their legs feel heavy. But I don't care a bit. I'm halfway through week 3 without any injuries or aches and pains and for me that's all the success I need.
But waking up to 50 degrees for my Saturday run would be nice too!