The rate of Russian ruble to foreign currencies including USD is based on the rates of Moscow Stock Exchange (MICEX). MICEX is the most reliable source used by the Central Bank to update its official rates.
Official USD/RUB* exchange rate on 15.12.2017 is 58.7082 RUB. This rate has been set by the Central Bank based on data of Moscow Stock Exchange (it sets the rates on 08:30 GMT as official for the next date). Several previous rates are as following:
See also History of USD/RUB rates
The most up to date USD/RUB rate is the current stock exchange rate which changes continuously and can be tracked online. At the moment (14.12.2017 16:45 GMT) it is 58.87 RUB for one USD.
Due to high volatility of ruble exchange rates long-term forecasts are virtually impossible. The official exchange rate may be forecasted maximum half a day in advance to it being set on base of stock exchange rates. At the moment USD/RUB rate is 58.87 RUB. So, it is possible to say that the next official rate is going to be somewhere close.
* Sometimes RUR is used instead of RUB as Russian currency code. RUR is the old code replaced by RUB now.