Now, the sensible way to find out is to go and buy a thermometer. But Robert Days are closed for the evening. So instead I dug out an Arduino kit I was given for my birthday (Elegoo's "The Most Complete Starter Kit for the Mega 2560") and set to work...

The answer: 27°C!
I'm using a DHT11 combined temperature and humidity sensor and a generic LCD display showing the results, running off of a 9V battery so I can wander around with it. The nice thing about Arduino development is there are libraries for everything, so there's surprisingly little code behind this: