"Because the weather is nice," Strange simply responds. There's a pause because that's obviously not the entire reason before Strange admits, "And I'm concerned about the leeches. That alleyway was swarming with them. If I see any more, I'll need to set them on fire."

This makes perfect sense in Strange's mind. He's obviously a bit nervous and tense about the simple idea of leeches. Guess who just discovered he's got a fun new phobia!