Dear Tom,
thank you for your letter. It is great to hear from you again. I'm happy your family are fine.
The news about your visit surprised me greatly! But don't worry, Russia is a beautiful country. You will definitely enjoy your trip. Now it is quite cool, about zero degrees Celcius. Sometimes it can be windy. I suppose, it might be freezing in the beginning of December. The temperature can vary from -5 to -10 degrees. So take your warm clothes with you. Nowadays winters are much warmer than in the beginning of the 20th century. The average temperature is about -5 degrees Celcius. There is a lot of snow, but it might rain as well.
I hope you will be excited visiting Russia.
Hope to hear from you soon.
Sincerely,
X