native weather app on the iPhone

iOS and iPadOS

Does anyone know, when the native I/OS weather app shows how much rain an area has received over what period that's for? I used to think it was since midnight of the same day but now I don't think so because the other day my area received multiple inches of rain, and I looked one time and it showed one number and then when I looked later that same day the number was lower. If it resets at midnight that number should've still been the same or higher since another midnight hadn't passed yet.