I'd like to know if a climate with snowy and gloomy winters and rainy and cloudy summers is possible. Because the climate of Russia in summer is sunny enough and the Icelandic ones isn't so snowy. So a climate snowy in winter and rainy in summer but with forests and the possibility to sustain life, what characteristics are required? I want an almost always overcast sky. Thanks for the answers. I forgot to mention that this type of climate, is for a Europe-like continent in a planet that orbits a star less bright than the sun.
Put your place between the ocean and a mountain range. Wet air coming in from the ocean tends to dump its water on the ocean side of the mountains. You get a climate like Portland or Seattle.
Put your place far enough north that it gets cold. Then the wet air dumping water will come down as snow. Possibly a lot of snow.
The ocean will prevent it from getting bitterly cold. The northern latitude will prevent it from getting too hot. You wind up with someplace like Anchorage Alaska or Buffalo NY -nice temperatures all year round, and near constant rain and snow.
Ursula K. LeGuin does a good job with this kind of environment in "The Left Hand of Darkness". Direct sunlight isn't needed, so long as there is enough radiant energy to grow some kind of crops, or to support a sufficient amount of wildlife for a hunter/gatherer society to live off of. A sunny region can produce 600 calories per square centimeter of arable land; an environment like you're describing might produce less than 100 per square centimeter, which puts corresponding restrictions on population size. It would probably demand a fishing industry, which could shift solar energy conversion to off-shore sources (like algae and other aquatic plants) and bring in essential fats and protiens from fish or aquatic mammals.
Technically speaking, you could create an environment with no solar energy at all, so long as you found an alternate source of energy to convert into organic sugars. Think about hydrothermal vents in the deep ocean, and their associated colonies of worms and shrimp and exotic bacteria, except on a massive scale... Not a place I'd want to live, thought.