OutSider is an app from The Weather Channel that combines the company's massive weather data with a user's fitness level, running habits, and goals. While the combination of these data sets work relatively seamlessly, additional features in the OutSider app don't quite work as well as they should. That being said, this free app is a great utility for those who exercise outdoors.
At its most basic level, OutSider takes a user's current location and personalized data to contextualize the current weather conditions in terms of a "run weather index". This index is a number from 1 to 10, with 1 being the worst possible weather conditions for running and 10 being the best. To make the index more relevant on a per user basis, there are customization tools so that runners can express which weather elements affect their running more than others (i.e. humidity, wind, temperature, etc.).
In addition to giving a live index reading, users can also drill down into a menu which provides extended forecasts, complete with the predicted weather's running index. In this menu, runners can schedule their own runs, add them to their calendar, and even use the app to help keep them accountable for how many runs they should be performing per week.
The attention to detail in these two aspects of the app are great, and the running index actually does feel like an accurate representation of how ideal running conditions are at any given moment. The app even goes so far as to direct runners to the "plan your run" screen if live conditions fall below a certain index threshold. All of these features make the app feel kind of like a must-have for runners, though not everything in OutSider app is perfect.
It seems that The Weather Channel is aiming for users to have OutSider replace their other running apps of choice, since it has tools built in to measure runs, attach heart rate monitors, create run playlists, etc. However, this functionality of the app just doesn't quite cut the mustard when it comes to other running apps like Runtastic, RunKeeper, or Nike+ Running. Although its functionality for the purpose of tracking runs is more or less the same, the app doesn't seem to reliably capture distances and times unless runners keep their phone screens on for the duration of the run. This, in addition to the tracker's basic interface, make it hard to recommend as a replacement run tracker.
So overall, OutSider is a pretty great weather utility for fitness purposes, though it is by no means a stellar fitness tracker. As a free app, I would recommend OutSider to any outdoor athletes to determine the best time to do their workouts, as the running index is great at its job. I would not recommend using the app's other features though until some updates come along and fix the issues I experienced with them.