For the most accurate temperature readings, it is recommended to mount the outdoor sensor in a shaded, well-ventilated location, such as the north side of a building (in the Northern Hemisphere), not in direct sunlight. This helps prevent false high temperature readings.
Yes, it saves rainfall totals over a period of time — specifically, it records hourly, daily, weekly, monthly, and total cumulative rainfall. The total rainfall is the accumulated value since the device was powered on.