How Many Months a Year Are Pleasantly Warm? Pleasant Months in the Climate of 1970 to 2000 and 2041 to 2060 from WorldClim

One simple way to describe how agreeable a climate is outdoors is to count the months whose average daily high falls inside a comfortable band. I count such months on the WorldClim 2.1 grid of monthly mean daily maximum temperature for 1970 to 2000 (10 arc-minutes) and on WorldClim's downscaled projections for 2041 to 2060 from three CMIP6 models under SSP2-4.5, and I weight the counts by land area and by the population of the 31,778 GeoNames cities of 15,000 people or more. With a band of 18 to 27 °C, land outside Antarctica has 2.5 pleasant months a year on average; 34% of it has none, 12% because it is too cool all year and 22% because it is too hot. The average person in these cities has 3.6 pleasant months, and 21% live where no month qualifies, almost all because it is too hot. In the three-model mean for 2041 to 2060, the city average falls to 2.9; 46% of city dwellers lose at least one month and 14% gain one. Cities with twelve pleasant months fall from 14 to 5 of the 560 with a million people or more, and in 38 big cities of the northern mid-latitudes a single summer season splits into a spring and an autumn. The direction holds for seven alternative bands and for each model separately. The measure ignores humidity, nights and rain, and the grid smooths mountains and coasts; an interactive map lets readers set their own band. Interactive version: https://tristan-hotham.github.io/pleasant-months/. Data and code: https://github.com/Tristan-Hotham/pleasant-months. Blog post: https://blog.tristanhotham.com/2026/10/28/pleasant-months/. Derived from WorldClim 2.1 and WorldClim downscaled CMIP6 data (Fick and Hijmans 2017; CC BY 4.0) and GeoNames (CC BY 4.0). The paper, data and figures are released under CC BY 4.0; the code under the MIT licence.