In every country except those three bastions of measurement freedom, Liberia, Burma and the United States, people measure their temperature in Celsius. It's a "scientific" system, with zero being the freezing point of water and 100 being the boiling point. On Gawker, Dennis Mersereau makes the case that Fahrenheit is a better system, one that is based on people and how they feel; 0°F is really cold, and 100°F is really hot. Whereas with Celsius, "you're cold at 0°C and dead at 100°C."
Since Celsius is based on water, it would make wonderful sense to use Celsius for the environmental temperature if we lived in water. Until we sprout gills and start flapping around the Gulf, we should use Fahrenheit for air temperatures.
He notes also that it is more precise because the unit is only 5/9ths as big, reducing the need for decimals. I would add that if you live in a cold climate that measures in Celsius, you can go for months without feeling positive about the temperature; Where I live just north of the border, it just climbed above zero last week for the first time since probably late November. Celsius is depressing.
Meanwhile, south of the border, there are so many newspaper articles about how much hotter it is getting, how many more days people have to suffer with it being over 100°. It is a meaningful number that people take note of, that people track in relation to the effects of climate change. That tipping point temperature is so significant that in the UK, the newspapers report cold weather in Celsius and hot weather in Fahrenheit.
As for the problems of using an American/Liberian/Burmese scale for temperature and and an almost universal one for everything else, who cares? It may be easier to figure out how many calories of energy it takes to boil a litre of water, but not a lot of people are going there. What do you think?