There is also a strong counter-argument to thieves preferring bad weather. Basically, it goes: when you are a thief, you want to do your trade with as few witnesses as possible, and to obscure any visibility of your actions to the witnesses there are. So, if you are thieving outside, you want it to be at a time when others want to be inside, and/or can't see you. Largely this means at night. Better if the weather is gross, so people are less likely to go out. Better still if they can't hear you over the rain. (If you are robbing suburban homes, you want to do it in the afternoon, after lunch, when most people are gone at work, and before the kids get out of school. For this example, the crime statistics I've seen, and anecdotes from cops back up the theory).