I do, however, have a rule of thumb, which is that a good way of working out what the weather might be like a year from now is to see what the weather is like today, and assume it's going to be more or less the same. This set us in good stead for our wedding - on September 19th 2008 I noticed that, despite our paranoid fears that a wedding on that date might run the risk of inclement weather, the weather that day was fine and sunny. Lo! and behold, on September 19th 2009 the weather was fine and sunny, and we had a glorious wedding day. Yay!
It is also comforting when the rule works in reverse. Exactly a year ago today, Sarah and I had set out on our boating trip on the Norfolk broads, and the heavens had opened and the wind was blowing mightily, and it continued to be a very windy, rainy holiday until things finally started to clear up about a couple of days before we were due to head home (by which time we'd more or less given up and spent the rest of the holiday moored up at Great Yarmouth yacht station).
And lo! and behold, although we're not in Norfolk (I have said I could quite fancy going back, but without the boat bit), I can report that here in Hemel it's wet, windy, and miserable.
I'd say I'm pleased to report that the rule works, but actually? Do not want. Dear wind and rain, please stop. Kthxbai.