It really depends on what you are comparing against. A temperature taken in direct sunlight at human height in a paved parking lot is going to be well over 10 degrees different than a grassy area shaded by a building. Even if they are adjacent areas. Proximity to a large body of water can easily change the temperature by 5-10 degrees.

A weather app is going to present a temperature that trys to average all of that for a fairly wide area.