Questions & Answers about Им будет холодно в городе зимой?
Why do we use Им instead of Они for 'they'?
In Russian, physical and emotional states like being cold, hot, or sad are expressed using impersonal sentences. The person experiencing the feeling is not doing an action, so they take the Dative case. Им is the Dative form of они (they). The sentence literally translates closer to 'To them it will be cold'.
Since 'they' is plural, why doesn't the verb use the plural form будут?
Because this is an impersonal sentence, there is no grammatical subject for the verb to agree with. The people (им) are in the Dative case, not the Nominative. In these constructions, the future tense always uses the default third-person singular form, which is будет.
Why does the word for winter (зима) change to зимой here?
Зимой is in the Instrumental case. Russian uses the Instrumental case for seasons and times of day to express 'when' something happens. So зима (winter) becomes зимой (in the winter), just like утро (morning) becomes утром (in the morning).
The word order looks exactly like a regular statement. How do we know it is a question?
You do not need to change the word order or add helping verbs like 'will' or 'do' to form a question in Russian. You simply use question intonation. When speaking, you raise your pitch on the specific word you are asking about, such as холодно, and drop your pitch at the end of the sentence.