If you read the manual, Canon says you should not use it below freezing, but I have found that above 0F is usually OK, it is a good idea to keep the camera in your jacket to keep the battery warm.
The snow is another issue. A few flakes quickly brushed off are not a problem, but a gob of wet snow allowed to melt on the camera is a no-no. Obviously there is a large range between these two.
Your camera is a tool. If you need to get the picture, you might have to take some risks. If the camera is damaged, time for a new tool. I took my T3i out on the tidepools and got splashed by a wave - I quickly dried off the camera, but that was enough for it to die. (The lens is still fine, though). I was upset, but knew it was time for a new camera, so I got my T6S.
Can I use my canon t6i in cold weather (10-20F) or when it is snowing, since it is not weather sealed, is the snow going to be a problem? Could the snow or cold damage the camera?
I do not advise it with a Rebel.
The lack of sealing means the cold will get into the camera faster, and any internal heat it generates will escape faster. It is a risk, wrought with unknowns. I would definitely wrap it up like a newborn baby. Do not forget to protect your lens, too.
The battery is very sensitive to the cold. It can register 0 volts on a voltmeter when it is exposed to 0F, but measure as fully charged when it is warmed up to a nominal 72F. Same battery. The only difference is temperature.
I have used my T5i for photographing winter wcenes, ice climbing events and ski races - all without a problem. Temps weren't down to 10F, but 15F was not uncommon.
Put a wether cover on and have a spare battery. As Wadizzle said, cold lowers battery performance but it returns wheh warmed up.. Swap them out as necessary and you should be fine.
Before you bring your camera inside to a warmer environment be sure to put iit in a plastic bag or something similar so you don't get condensation - it will fog up optics and take a while to disipate.
Same hold true going from an air conditioned environment to a humid outdoors.
Even though most of the guys say no to easycover, I love mine. Not an excuse to abuse the camera or expose it to water / snow / temp extremes, but adds a layer of protection $30. I've put one every canon I've owned. Locally available too.
Bay Area - CA
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Forget the cold. Not a problem. Do as instructed above by keeping a second battery in an inside pocket.
"...when it is snowing..."
Snowing or snow storm? Snowing has never hurt any of the dozen or so Rebels I have used in the past. There are great shots just waiting when there is light snow falling. Go catch them. Neither Rebel nor I will be outside in a snow storm!
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