People enjoy backpacking more when they're comfortable. That's the main reason why people go light (or refuse to go light) in the first place. It's not a problem if the weather is going to be cool  and dry all the time but in some places, things can get both wet and cold and staying comfortable may not be as easy.

While it's not very likely that you'll stay completely dry in prolonged wet weather, you can still aim to stay reasonably comfortable. The choice of backpacking gear will have a big effect on how your experience backpacking in the cold and wet weather will be.

Most packs (if not all) are not totally waterproof so you'll need to take additional steps to ensure that your backpacking gear stays dry. One way to keep your belongings dry is by using a pack cover. You can also use pack liners which are much more convenient because you have easy access to the contents of your backpack since there is no need to remove the cover.

The simplest way to keep you pack dry is by using a trash bag as a cover. It cost almost nothing and you can also you use it as a trash bag as it's supposed to be.

When cooking inside a vestibule, you need to make sure that the stove is stable or you risk burning down your tent. Position the stove so that if it tips over, the flame does not touch anything that can burn.

I only use canister stoves inside a tent because a liquid fuel stove might cause a flare up and alcohol stoves are just too slow for me.

Also make sure the vestibule is wide open to allow for ventilation. Carbon monoxide poisoning can cause dementia and even death.

Sleeping bag temperature ratings are not accurate because how warm a sleeping bag keeps you when you sleep depends on many factors including metabolism, weight and bodily hair.

You should take extra care in keeping your sleeping bag dry because sleeping wet and cold is not only uncomfortable, it can even kill you. Synthetic bags can still keep you warm even when wet and they dry very quickly.

However, down sleeping bags are more comfortable and keeps you warmer compared synthetic bags with the same weight. You just have to make sure that you keep it dry.

In a cold environment, a sleeping bag may not be enough to keep you warm at night. In fact, you can lose more heat to the cold ground than from anything else. You can choose any type of camping pad which suits your comfort needs but make sure that it can also keep you warm.

Some inflatable pads are not suitable for winter but you can remedy this by using it in combination with a foam pad that has a high R-value.

Camping in wet weather can never be enjoyable if your tent is not stormproof. A waterproof tent will help keep out the rain but when it's cold and raining you can also get wet from within the tent through condensation.

Water can also reach you from under the tent so one with a footprint is highly recommended. Choosing the right site to camp can also help keep you dry.

Condensation is likely when ventilation is poor or when the tent is too small for you that air flow is restricted. You sometimes need to open up the tent door a little bit to let out moist air and prevent condensation at the risk of letting in a little bit of rain.

Single wall tents have excellent ventilation but it can get quite cold when it's windy. Double wall tents are warmer and if the inner walls are made of solid fabric, it can be drier as well as condensation only happen on the outer walls in most cases.

A vestibule is important when camping in cold and wet weather. You need to have a roofed area outside of sleeping area for storing wet gear and for cooking when needed. A vestibule is also great for ventilation and for your own safety, only cook inside the vestibule with good ventilation.

Dressing in layers has many advantages. One of the most important is that it can perform different functions that can keep you warm. The first should be something that is quick drying and wicks away sweat because it gets really cold when you're wet.

The second layer is the insulating layer. Wear something that can keep you reasonably warm even when wet because several days in the rain will likely get it wet even when you're using a good outer waterproof layer.

The same layering can also be applied to your lower body but many prefer normal trail pants. Some like to wear rain pants over long woolen underwear while others have a preference for windproof, quick drying synthetic pants.

Some people like to use snowboarding pants or other waterproof pants when it's really cold. I highly recommend using pants that are waterproof as well as breathable.

Other important items in cold weather are headwear and gloves. I never leave my balaclava behind.