How many countries primarily measure their temperature in Fahrenheit?
There are only five (5) countries in the world that still use Fahrenheit to measure temperature, the Bahamas, Belize, the Cayman Islands, Palau, and United States.
Territories associated with the U.S. (Puerto Rico, Guam and the U.S. Virgin Islands) also use the Fahrenheit scale for every day applications. Scientific communities around the world use either Celsius or Kelvin. The United Kingdom occasionally uses Fahrenheit, but it pretty much only uses it to placate Americans. Their official temperature scale in the UK is Celsius.
About 5 or 6 decades ago, most English speaking countries switched over to Celsius, with the United States being the most noticeable exception. Some experts say that it is easy to convert Celsius to Fahrenheit, multiply by 9, divide by 5, then add 32. So, maybe the U.S. should join all the other knowledgeable countries around the world and use the Celsius scale.