Will it rain next weekend?
I know this because of the high pressure area that's currently sitting here and will take time to move.
Last weekend, however, it would have been practically impossible to tell whether it would rain here or not. There was a low coming in off the Atlantic, and if it had gone a little further North or South, it would have rained there instead of here.
Forecasters are nearly 100% accurate with what the weather will be. It's just the time and location of that weather that are tricky!