As someone with a huge aquarium, I've gotten used to water feeling "cold" to the touch as I keep mine at 75F and with how convoluted water changes are with it (linking multiple hoses from the basement to the main floor since none of the sink faucets can be attached to for some reason) I've had to learn how to judge temperature that way.
Of course, I still utilized an actual digital thermometer when I had to give my BP soaks after his bad shed to ensure it was a cozy 80F.