Wearable Alert-inator 3000

What I'm making is a simple temperature sensor, something that will tell me the temperature of the bath/shower water in the morning. Getting to school is always a rush, and it takes a lot of time for the water to heat up, so this will alert me (with pretty little blinky lights) when the water reaches the preferred temperature. I just put it on the faucet, and when it becomes the right temperature, LEDs on a bracelet I'll be wearing will light up and tell me that the water's ready.