If you want super quick access to weather information on the fly with your smartphone, there's no arguing that Google Now is probably the quickest way to get it, short of adding a widget to your homescreen that's there immediately after you wake the display and unlock the device. If you want a little bit more detail, you can go for something like Dark Sky, an app which just landed on the Play Store today and claims to offer the most accurate hyper-local weather information of any other application available. The app, which makes the jump from iOS, is extremely popular and it won't be surprising to see this gain quite a following on Android. It is worth noting that the app on Android is free to install but does have a subscription fee associated with it, while users are stating that it is or was a one-time buy on iOS, causing some to be unhappy with the developers on this decision.
Moving beyond that, Dark Sky offers up not only what appears to be incredibly accurate weather information with down-to-the-minute forecasts, but it also has a UI that isn't too shabby and is easy on the eyes. Inside you'll find 24-hour forecasts, 7-day forecasts, the conditions of the current time when you open up the application and a series of detailed weather maps.
Dark Sky also offers things like rain notifications and alerts which as they suggest, keep you informed of when you should be reaching for that jacket or umbrella before you walk out the door. Alongside this, there is also a widget you can place on the homescreen, and there are personalized daily summaries that appear on your lockscreen after you configure the summaries initially. As stated above, you also get down-to-the-minute forecasts, but this feature, along with the summaries, rain alerts, and widget, is part of the Dark Sky Premium, which costs the user $2.99 a year to get access. If this sounds like a set of features you'd like to have, you can try Dark Sky Premium out with the free two-week trial, and after that begin paying the monthly sub fee. If you don't care for the sub fee, you can utilize Dark Sky's initial offering which doesn't cost anything, but consider that $2.99 a year is not a huge cost for the use of the premium features.