This video teaches you
If you need to check water temperature for yeast without a thermometer, adjust the faucet until the water feels very warm but not too hot on your wrist. At that point the water should be around 105° F (40° C), which will work great for most yeast. To check water temperature without a thermometer for tea, fill a pot with water and place it over high heat. Once tiny bubbles start to form on the bottom of the pot, you can estimate that the water is around 160° F (70° C). Once visible steam starts to rise from the pot, the water is around 170-180° F (75-80° C). When large bubbles start to gently break the surface of the water, it’s around 190° F (90° C). When strings of bubbles start rising to the surface, the water is 200° F (95° C). Finally, once the water is at a full boil, it’s close to 210° F (100° C).
