Do your feet get hot and sweaty?
This is going to sound weird, but you need a product called Toasty Feet! They're insulated insoles made by Polarwrap. They put an insulating barrier between the bottom of your feet and the floor... or whatever surface you happen to be standing on. If the floor is cold, Toasty Feet keep your feet warm. If you're standing on a hot macadam parking lot, it keeps your feet cool!
Polarwrap actually makes two identical products... Toasty Feet Insoles and Insulator Insoles... with different names and packaging because using Toasty Feet to keep your feet cool just doesn't sound right.
I simply stock the Toasty Feet to keep things simple and explain why they work year round. You put the Toasty Feet in your shoes and just leave them there and your feet are stay comfortable year round.