Different types of teas require different steeping temperatures to brew properly. There are a few different methods to achieve the optimal temperature. Some people may choose to use a food thermometer. I personally prefer to use a kettle with a built-in thermometer. However, not everyone has access to these useful devices. Given that tea-making far predates the invention of thermometers, humans have developed a less technical way of measuring water temperature. The method detailed below isn't as precise as using modern technology, but it will work just the same.
A Guide to Determining Water Temperature:
As water boils, it goes through multiple stages. These stages can be told apart through both visuals and sound. There are five stages.
Stage 1: 155°F-174°F
In this stage, the water has just started to heat up. You can identify this stage by the small, pinhead-sized bubbles that rise to the top and pop. Water at this temperature is best for steeping more delicate green teas. These teas often burn easily. Thus, they require a lower water temperature.
Stage 2: 175°F-179°F
Water in this stage can be identified when the bubbles are still small but slightly larger than in step one. There will also be vertical wisps of steam above the pot. This temperature is best suited for Chinese green teas, green oolongs, and white teas.
Stage 3: 180°F-185°F
At this stage, large bubbles will begin to form on the bottom of your pot. The water will also start to make noise.
Stage 4: 195°F-205°F
At this stage, the water is just below a boil. This stage can be identified by the continuous strings of bubbles rising to the water's surface. Water at this stage is best used with darjeeling teas, dark oolongs, and lighter black teas.
Stage 5: 212°F
Water at this stage has finally reached a rolling boil. This temperature of water is best used with stronger black teas (like breakfast teas), most herbal teas and pu'erh teas.
I hope you found this article useful.