Normally the thermometer has a method of showing the highest and lowest temperatures in a period of time. So if you wish to check what the temperature reaches when you are not there then you do have to reset the high and low marker every day.

I have one of those thermometers that Owdboggy has mentioned, and yes you would have to reset it to get the desired timescale of temperatures.

Pretty much what Owdboggy has already said. LOL.

Many thanks , l will give it a try....Buzby