I wouldn't mind a place where it was 40 every night and 55 every day. I, like the OP, prefer it cool. I think my favorite times of the year (both in general and for commuting) are late October-early December and late February-early April.

That being said, one thing (of many) that bike commuting has been good for is helping me to get acclimated to the weather conditions of each season just by being out in it more. While I'm not a fan of the heat, it doesn't bother me too much anymore (especially when compared to my wife who complains about it constantly [she doesn't ride]), and I chalk a lot of that up to being out in the heat doing exercise for 60 minutes every day. I used to have the same thing when I worked outside in the summer heat during breaks from college -- it helps you to get used to it.

Likewise, winter cold bothers everyone else a lot more than me. I think it's a similar phenomenon.