One of the most straightforward and informative home weather stations you can buy this AcuRite weather station acts as an indoor/outdoor thermometer an indoor/outdoor hygrometer and a weather clock that automatically adjusts for daylight saving time! As mentioned the included atomic clock provides split-second accuracy so if you have a programmable alarm set on the display you?ll always know exactly when the temperature or humidity has met or exceeded your customizable minimum or maximum value! The indoor weather station is AC-powered and can take three (3) AAA alkaline batteries (not included) for optional battery backup in case of a power outage. The wireless outdoor sensor requires two (2) AA batteries (not included lithium recommended for optimal performance).