I'd say, looking at those figures you have the temperature prbably about right but it is more about the indoor temperature. You can assumeit will be 24 when the aircon is on of coarse but what happens when that goes off, do you feel it gets colder or warmer or is it quite consistant ,
The easiest thing to do is get a thermometer and test the tank during a 24 hour cycle, or get one of those stick on the tank ones which make it easier, like this one, very cheap and you should be able to get one easiliy localy I would think,
https://www.pro-shrimp.co.uk/aquarium-thermometers/1072-jbl-digital-aquarium-thermometer-4014162614063.html?search_query=thermometer&results=43
It may not be laboratory accurate but gives a rough idea of how it is fluctuating without keep doing it all manually.
Simon