Every winter I decide I want to get a thermometer with wireless connection to a unit inside. This year I am going to get one! I'd like one that records the lowest/highest temp during a certain period of time.
There are many. I have had many. The one that has last the longest is the german make TFA - the clock will always be an hour ahead registering their time. But that's no problem. You do have to insert one battery and then the other within 30 seconds or so, and then get the connection going with all of them. The battery compartment of the outdoor sensor can be fiddly as has a small screw that has to be taken out and re screwd. All sensors must be out of direct sunshine. I love mine and in winter I record MIN in the night out and indoors every morning.
We got the TFA one for the PILs for Christmas, they seem to be getting on well with it, despite being technophobes. We have an "ascot" one from Aldi, does everything I want it to do, although the "weather prediction" icons are rarely right, as they're based on pressure and temperature changes.