A taiga is an area of open vegetation with shrubs, low conifers and, in Eurasia, birch. A taiga is a transition zone between the boreal forest and the Arctic tundra. The forest cover, whose composition is similar to that of the boreal forest, is continuous but relatively open. The subarctic climate is marked by short and cool summers with prolonged periods of sunlight and very cold winters. The average temperature during the warmest month is between 10 and 15°C but the minimum average during winter may drop below -30°C. Precipitation is generally lower than 500 millimetres per year.