I asked a friend that happens to be a meteorologist to give a quick take on his favorite weather apps and here's what he said:
I will review free weather apps using the Samsung Galaxy Note 4. For the best "all inclusive" weather app, I lean towards Weatherbug (iPhone, Android). There is nothing wrong with AccuWeather or The Weather Channel apps, but for me, Weatherbug has the cleanest interface to quickly get to the information I want without having to scroll or swipe through a bunch of rubbish. These other "big box" apps seem to push too much detailed information that give the façade of abilities, such as being able to forecast weather events minute by minute. The Weatherbug radar and forecast interfaces are easy to locate and navigate. The widget is very useful with several options of footprint sizing.
For primary standalone functions, I like NOAA Forecast (Android only, but several iPhone apps use NOAA data) and MyRadar (iPhone, Android). Nothing fancy here, just good, reliable, and easy to use apps. MyRadar allows for seemless radar transition between locations on a map with some cool overlays. NOAA Forecast is just that...the National Weather Service forecast from the source of most weather model data.
I haven't found my perfect iPhone weather app yet, at least not a free one. I used Yahoo Weather for a while, but deleted it a few months ago after an update began using the GPS 24/7 (this appears to have been fixed). I went back to the stock weather app and appreciate its minimalism and lack of ads. I'm trying out a few other apps for localized precipitation data.
Storm (iPhone only) and Radius (iPhone only) are both from Weather Underground and perform the same function with different interfaces. That function is to notify you of nearby precipitation, lightning, and National Weather Service alerts. I have Storm set to use GPS 24/7 to track my current location, but the app hasn't shown up on my battery usage list yet. They both seem to be fairly accurate, and I like getting a notification instead of having to check an app. Dark Sky ($4, iPhone only) is similar app with positive reviews, with the added feature of notifying you before the precipitation begins. I'll give it a try one of these days when I've exhausted other free options.
I like what AccuWeather (iPhone, Android) claims to do with MinuteCast, an easy way to see precisely when it will start and stop raining in your local area. It hasn't been terribly accurate for me, perhaps because precipitation is somewhat unpredictable in San Francisco or as Dan said above claiming to predict weather down to the minute is a 'facade'. The iPhone version has a Today Widget to quickly access MinuteCast.