Earlier this week Forecast.io was announced by the same team behind the iOS weather app Dark Sky. The app would provide alerts based on the immediate weather forecast, allowing you to get inside just moments before the weather would get nasty. With the launch of Forecast.io, the team is able to get the same type of forecasting into the hands of more users since it's a Web based app.
To use the app simply visit Forecast.io using your browser. You can then create a Web shortcut and save it to your mobile device, or a bookmark on your computer. The forecast is broken down by the hour, allowing you to see exactly what the weather is going to be like at a particular time.
The Time Machine feature is particularly fun, allowing you to type in any date and see what the weather was like on that day. Or you can type in a future date and see what the weather should be like. Time Machine isn't available on mobile devices yet, but you can access it right now on the Web.