Last year Nolan Gray mapped out “the cities of the world where you don’t need AC or heat.” And just recently he updated his data with the help of Guardian Cities for their “sweltering cities” series. As part of the study, they projected out average temperatures, in both the summer and winter, to 2059, showing which cities may become more dependent on air conditioning. The answer looks to be many.
In his original study, Gray had 9 climatic categories, all of which were based on average high and low temperatures throughout the year. Category 1 was you definitely don’t need AC or heat. These cities are essentially perfect year round. And category 9 was you definitely need heat and AC. These cities are basically the worst places on earth to occupy from a climate perspective.
Here is that climate classification system in lovely chart form (note his caption):