It works most of the time!! Simple math to get you the temperature from Celsius to Fahrenheit for those Fahrenheit people!! So if it is 30 degrees Celsius in summer day in Tokyo, you multiply by 2 and add 30. So it will be 90 degrees Fahrenheit. Got it? It is not super scientific accurate number but give you the ball park. Hope this helps. I don’t want you to be freeze to death or sweat you to death.