It's currently 80.4F and yesterday's high was 61.8F. It's a good time to check to make sure the air conditioners are working properly before it starts getting hot. Also bought and installed a little wireless "weather station" as they call it from Wal-Mart. Acurite Model #02038W
The main box does require being plugged in. Has battery for backup. The remote sensor (hanging outside) runs on batteries. Nifty. Now I will know how hot/cold it is before I step out the door in the wee hours. Works for me and that is all that is important.