The cold wave now affecting the northern hemisphere is a meteorological phenomenon caused by the large-scale blocking of atmospheric circulation on a major North-South corridor. The phenomenon is well known by meteorologists and is generally linked with atmospheric oscillations, such as the Arctic oscillation, which has been relatively powerful since mid-December 2009. The blocking episode is nearing its end, and the northern hemisphere winter is now reverting to its normal features from the West and South in Western Europe. Some severe episodes will no doubt linger in several regions of the world and during certain periods of the winter season, which is quite normal.
For more detailed information on the situation in any specific country, please contact the corresponding National Meteorological and Hydrological Service.