Here are possible completions for the sentences:

1. It's **pouring** with rain outside. The children will get very wet.
2. What are the main **causes** of global warming?
3. It's usually cold in January, but this winter it has been very **mild**.
4. Unfortunately, it’s very hard to **predict** the future: anything could happen.
5. It was very hot, but fortunately there was a lovely **breeze** coming off the sea.
6. Global warming is causing more **extreme** weather conditions, which will **affect** people in different parts of the world in different ways.