Do you find that the first time you hit a particular low temp, such as 30F, you dress according to your guide here but later in the season when the temp goes up to 30F, you need less? I have found that. It used to be that between 10 and 5C (~50-40F) I'd need tights over my shorts but later this "fall", when I rode in at 0C/32F (wearing tights over my shorts and long merino socks) and then rode home at 5C, I was perfectly fine in just shorts and short socks.