Before you ride your ATV in cold weather, you need to do a few extra things to make sure your ride is a safe and enjoyable one.
A few cold weather preparations will make sure all your cold weather days of riding are good ones. If you are going to ride your ATV, never ride alone. Make sure someone knows where you and a buddy are going to be riding as well. If you are stranded in the extreme temperatures that Winter tends to bring, time is of the essence in finding you.
Do a pre-ride check on your ATV. While this is always a good idea, in cold weather it is a necessity. Look over your ATV carefully, inspect the frame and be on the lookout for cracks or damage; clean and then grease electrical connections with dielectric grease; clean, then grease chassis lube points. Replace all fluids with lubricants and coolants appropriate for expected temperatures; lube control cables; cable lubrication helps avoid frozen,useless cables in the field. If you're going to be riding your ATV in the snow, reduce your air pressure a little bit to get a better footprint on the snow.
A good trick when you're riding the ATV trails is to hit your brake levers occasionally to prevent them from freezing up. Stop and check your ATV every so often and clear the snow and ice from around the CV and U joints. And because ice and snow are heavy, carry extra gas. Make sure that you carry extra water as you can become dehydrated quickly in cold temperatures.
Riding your ATV in the Winter can be a blast if you just do a little prep work in the beginning and you'll have a great time on your ATV.