I'm such a WIMP!!! I was FREEZING at 40 degrees last week! In fact I have a 56 miler to do this morning and I'm putting it off till it warms up a bit so I don't have to pile on the clothes!
Now as for the summer... I'm pretty good in the heat. I'll go out up to about 112 f as long as it's late afternoon and I know the sun will be setting soon. In the summer I usually go out about 5:30 pm and ride until dusk. Usually my biggest worry when it's that hot is that my tires are going to explode!
I guess I'm a psycho but I actually LIKE to ride in the heat... go figure?!
I guess thats why I never looked back when I left soggy nor cal for Phoenix.