Answer
If "twice as hot" is taken literally, twice the internal energy means the temperature in St. Petersburg is twice the current absolute temperature in Boston. The temperature in Boston of $40^{\circ}F$ is about $4^{\circ}C$ , which is 277K.
$$T_{S.P.} = 2(277 K) = 554 K$$
Convert the absolute temperature in kelvins to the Celsius temperature scale by subtracting 273, which is $281^{\circ}C$, or close to $540^{\circ}F$ .
St. Petersburg is not "twice as hot" as Boston!
