Keep in mind, though, that it is important to be careful with your knees. I have seen it so many times over the years in those first few warm-weather rides—guys riding in shorts with nothing on their knees.
I'm not saying that you have to ride in full tights, but it is a good idea to keep the knees covered with at least half-tights or knee warmers (short sleeves of lycra that fits over the knees and under the shorts).
I recommend that temperatures above 60 degrees F are OK for riding in shorts, but for anything below that—even if it is sunny—you should keep your knees covered. Some might even consider raising the cutoff to 65 degrees F.
You have worked so hard over the winter, the last thing you want is to develop a knee injury this close to the race season.
Simple preventative measures will save you some potentially serious heartache. Enjoy each day and I look forward to seeing you out at the races.