I think the use of "balls" as an exclamation is more British English than American English. Balls (and bollocks!) is used usually to express annoyance regarding a situation, or rejection of something previously said. Like, if you were to say to someone "Don't talk balls!" or "That's utter bollocks!" -- you're essentially telling them they're spouting nonsense. Or, if you're at the airport and find out your flight's been delayed, you might utter "Oh, balls!" to show your annoyance with the situation. So you wouldn't really use it in the sense you did here with regards to the weather -- unless the weather forced you to cancel plans, to which you could say, "balls!" in frustration/annoyance.