If you're flying, taking the train, or otherwise heading somewhere the weather could be different, visiting isitraining.in could be a day saver. Add a slash and your intended city after the URL, and you get your answer to "Is it raining?"
So entering isitraining.in/sydney gets you the yes/no answer and some basic weather details. Some cities or towns may require adding a state or country after the name — isitraining.in/syracuse-italy and isitraining.in/syracuse-ny are two very different places, after all. Handy stuff, when it's available. At the moment, their servers seem to be taking a hit, so perhaps a bookmark is required for later perusal.