The Good: Dark Sky gives you alerts for impending precipitation with an intuitive interface, and has the potential to be eerily accurate. The Bad: Predicting weather behavior isn't a perfected craft, so it can give you false forecasts, especially in remote areas. The Bottom Line: With accurate weather alerts that are specific to your exact location, Dark Sky is a must-have app for iOS users. Dark Sky is a weather app that will make you do a double-take when you realize what it's capable of doing. Instead of just giving you the standard weather forecast (though it does that too), the developers of Dark Sky opted to go one step further and proactively alert you when nasty weather is heading your way. Predicting the weather is obviously not an exact science, but by using your exact location, Dark Sky is able to pull in data and tailor the app to give you the weather around you. It might be a bit pricey (currently at $3.99\/\u00a32.49), but the peace of mind you get in knowing you won't be caught in the rain is worth it.Checking the weatherLike Apple's own Weather app, Dark Sky is able to provide you with current weather stats in addition to a forecast for the next seven days. But the layout it uses to display the information is a bit different than what you find in Apple's offering.In Dark Sky, the default screen displays current temperature, "feels like" temperature, sky conditions, and a forecast for precipitation over the next hour. Along with the basic information, an hourly graph is constantly displayed, showing you the level of precipitation to expect over the next hour. Tapping anywhere on the screen will also display the current wind speed and direction, humidity, barometric pressure, and visibility.Conversely, Apple's Weather app (which is only available on the iPhone) displays the current temperature, hourly forecast, and a forecast for the next seven days all on one screen. A small amount of additional information is available by tapping on the screen, but it lacks a precipitation guide, among other features we will get into in a minute.To view more in-depth information in Dark Sky, you'll first need to learn how to navigate the app.Navigating the appNavigating through Dark Sky is accomplished by using a combination of gestures and taps. As I just mentioned, tapping on the main screen reveals extra current weather stats. Swiping from left to right will reveal an animated radar map displaying either precipitation or temperature. (Radar is something you won't find in Apple's weather app.)Swiping in the opposite direction (right to left) reveals a 24-hour forecast in graph form, cloud forecast, and sunrise and sunset times. Another swipe in the same direction brings you to a seven day forecast. Each day has the forecast high and low temperatures along with percentage indicating chance of precipitation. Tapping on each respective day will display the hourly forecast for the day.Navigation throughout Dark Sky is fluid and intuitive. After getting the general idea of what the various gestures were, I was able to quickly view the information I wanted without much effort.