In describing the most terrible day in my life, which paragraph is correct?
1- It rained very badly, I couldn't see anything. It was the worst day of my life.
2- It rained very haevily, I couldn't see anything. It was the worst day in my life.
You would use heavy/heavily when describing rain (heavy rain/rained heavily).
You would only use good/bad when describing the weather itself or conditions.