Hidden mining using the service CoinHive has become so widespread that it to public sites.
It is noteworthy that its existence does not in any way hidden, the script is installed at the beginning of the HTML code and not hidden in other files are not obfuscated and is not masked by other methods.
Perhaps the site has become a victim of hackers, as, for example, the websites of public bodies in the UK and Australia, but there is a possibility that a hidden mining are concerned with the technical experts of the Ukrainian hydrometeorological center.
Scripts for covert mining is defined by most antivirus programs as malware. Their work in the browser may cause 100% load of the computer and freeze, resulting in data loss and other unpleasant consequences.
From October 2017 the script CoinHive ranks 6th in the list of the most common malware.