Staying in megapolis during such heat wave is not only rather hard, but dangerous. That is in Moscow so-called "cool rooms" were opened at the Centers for Social Protection. At these places you can enjoy free water, relax under the air conditioner, and even get some medical help.
The centers are open from Monday to Thursday from 9.00 to 20.00 on Friday from 9.00 to 18.45, on Saturday from 9.00 to 17.00.