Sounds like your winters are about the same as we have here..
Is your gelding turned out or in a stall more? Does he get a thick winter coat? Do you clip him?
Until I learn a little more about his situation, I would suggest an average medium weight turnout blanket. It's wind and water resistant, and will hold up to the elements.
If he's clipped or doesn't get much of a coat, something a little heavier may be better, or you could layer a light stable sheet under his medium weight turnout.
The Weatherbeeta Orican is well made and super long lasting.
For summer, he doesn't really need anything, unless you want to get like a fly sheet, light anti-sweat or a cooler for him.
My gelding has a medium turnout, neck cover, anti-sweat, and a slicker for taming his mane. When I'm trailering in the rain, I'll use all those at once sometimes. Other winter days, he's just in his turnout, and for trailering I'll put him in his hood for the wind protection. That's all he has, and is quite comfortable.
"You're just as sane as I am."~Luna Lovegood.