Copenhagen is in the oceanic climate zone. As the city is in the path of Atlantic low-pressure systems, Copenhagen experiences unstable and changing weather patterns in all four seasons, as well as temperatures about 5 degrees higher than average for its latitude (55 degrees North) worldwide. The main reason for this warmth is the Atlantic Gulf Stream, which moves warm water from around the Gulf Coast area toward Europe, and the low-pressure systems follow with the oceanic stream.
Precipitation is moderate throughout the year, with a small peak during June to August. Snowfall occurs mainly from late December until early March, but snow cover seldom lasts long. Rain during January and February is as common as snow, and the average temperatures for these two winter months is near the freezing point.
During winter, the weather is dependent on which latitude the Atlantic low pressure centre takes. With a stable high-pressure system around the Alps, the low pressure from the southwest moves toward southern Scandinavia and northern Germany, producing above-freezing temperatures day and night. When a stable high-pressure system sits over Denmark or the lands to the northeast (such as Finland or Russia), the mild Atlantic winds from the southwest are blocked, allowing polar winds to cover the area, and the temperature dips to below freezing (rarely below −5 °C (23 °F) during the day and −12 °C (10 °F) during the night). If the European continent experiences cold due to the eastern Russian winds, which rarely occurs, it can "freeze from the south". This was a phenomenon that took several centuries to understand.
Spring is comparable to continental Europe, but delayed about a week because of the cold surrounding water. On the other hand, in late autumn Copenhagen is kept milder due to the same factor, but reversed. In late November and December the surrounding ocean water is generally warmer than the air. From mid-October to February, one or two
