I can't find confirmation to this in Russian news, which strongly suggests that this is fake news. If such a record were set, it would beat the +37.3C record set in 1988.

Note that the article says "if verified", which you should read as, "we just published this without verifying".

Here's apparently where everyone is getting this from: http://www.pogodaiklimat.ru/monitor.php?id=24266

Don't know about you, but to me the site does not look very credible. Other sources (such as http://www.hmn.ru/index.php?index=8&value=24166) suggest the temperature got up to 36C that day.