Tempest Weather Data

Does anyone know where the weather data for the highs/lows are being pulled from? I notice that mine fluctuates quite a bit and is often not nearly as accurate as AccuWeather. An example from today; this morning when I awoke at 5:45 AM the Tempest app said the high would be 79. In the afternoon it changed to 77. Now it changed again and is showing as 73, but I am already sitting at 74.8 (which is obviously higher than the newly adjusted high is showing).

Does anyone have any info on where the data is being pulled from to populate future weather and why when the high adjusts throughout the day it is often lower than what the current temperate is?