Explanation:

- Come rain or shine is an idiom expressing determination to do something, regardless of any difficulties.

- Option 1: When it does not rain

- This interpretation is too literal and doesn't fit the idiomatic meaning.

- Option 2: In the monsoon

- This focuses on a specific season and doesn't capture the intent of overcoming any challenge.

- Option 3: Whatever happens

- This means continuing an action regardless of any obstacles or events.

- Option 4: In bad weather

- This is overly specific and misses the broader meaning of persistence.