Is there some phenomenon that would cause rainwater to smell bad?

Here in NC, we’re experiencing a lot of heavy showers and thunderstorms because of a low pressure system parked offshore. On two separate occasions over the last week or so, the start of the rain has been accompanied by the smell of sewage, or sulfur. My partner has also noticed the smell, so I feel pretty sure that it’s a legitimate occurrence. (She often accuses me of having a “dog nose” because I have an acute sense of smell, but she noticed the same thing independently.)

Why would the rain smell?