How cold do you ride in shorts during spring?

[shootingstar]

Our spring days starts off in morning, around 5 degrees C or even zero and climbs rapidly to 22 degrees C. Clear skies and bright sunshine all the way.

It gets kind of annoying...figuring out what to wear without carrying a lot, especially on the bottom side. So I wear short walking shorts (meaning 9 inches above my knees + short sleeved jersey, very thin, moisture repellant vest and light cycling jacket with back vent). Every spring I go through this: To "harden" my legs to initial cold. Then in about 1 hr., the weather is fine for my legs.

Meanwhile, I see joggers in their sleevless tank tops.

Frankly, I'd rather stick to my short shorts/temporarily cold legs, rather than sport a tank top in those near freezing temperatures in morning.