Guessing temp after boiling water by time elapsed??

I use a closed-off, opaque kettle on the stovetop and use a similar method to what wokeupfuzzy described:

160-170: Vapor appears at the spout of the kettle; may be difficult to see except up close.
170-180: A small amount of white steam appears above the spout in short bursts.
180-190: A steady column of white steam appears but breaks and curls off to the side.
190-200: A nearly-straight, unbroken column of steam appears.
200-211: Boiling may begin; the kettle starts whistling at low pitch.
212: Kettle starts whistling at high pitch and boiling is very vigorous inside kettle.

Note that I am very close to sea level and I have never technically measured these temperatures, but based on observation and the resulting cups of tea I’m pretty sure this is accurate. So far all the tea I’ve made using this model has been steeped correctly!

Found this answer on a blog :

Assumptions: 1) boiling water in an open pot, 2) Room Temperature is ~70 degrees Fahrenheit.

White Teas: 170-175 degrees Fahrenheit, 6 minutes
Oolong Teas: 180-190 degrees Fahrenheit, 4 minutes
Black Teas: 190 degrees Fahrenheit or greater, no more than 4 minutes

Green Teas:
140 degrees Fahrenheit, 14 minutes
160 degrees Fahrenheit, 9 minutes.
170 degrees Fahrenheit, 7 minutes;