Questions & Answers about tiānqì rè de shíhou, wǒ gèng xǐhuan hē bīng chá.
In this sentence, 的 links a descriptive phrase to 时候.
The pattern is:
[clause / description] + 的时候 = when ... / at the time when ...
So:
- 天气热的时候 = when the weather is hot
- literally: the time when the weather is hot
This is a very common structure in Mandarin. You can use it with many kinds of situations:
- 下雨的时候 = when it rains
- 我小的时候 = when I was young
- 有空的时候 = when one has free time
That is a very common question.
When an adjective is the main predicate of a sentence, Mandarin often uses 很:
- 天气很热 = The weather is hot
But here, 热 is inside the phrase 天气热的时候, which is acting like a descriptive clause before 时候. In that position, 很 is often omitted unless you specifically want to emphasize very hot.
So:
- 天气热的时候 = when the weather is hot
- 天气很热的时候 = when the weather is very hot / when the weather is really hot
Both are possible, but the version without 很 is very natural here.