Tourists cover their face with hands to keep warm in Helsinki, Finland, Jan. 5, 2017. In the initial days of the new year, Finland has been experiencing a sudden drop to winter temperatures. Authorities have given "frost warnings" to remind residents to keep warm and to avoid risks of health impacts. In the capital city of Helsinki, located in the southern coast area, temperature dropped to less than minus 19 degree Celsius early Friday, whereas in Muonio, northwestern Lapland, temperature was minus 40 degrees Celsius on Thursday. (Xinhua/Sergei Stepanov)