Weather has always been a popular category with many popular Weather APIs listed in our directory. While XML is still the leading data format used, the trend of JSON becoming the developer's choice over the last few years is also reflected in the Weather category. Since the beginning of 2010, JSON is the leading data format used by Weather APIs with 11 added to the directory out of 12 JSON weather APIs. The chart below shows the breakdown of APIs using various data formats. HAMweather Aeris, the first Weather API added this year continues the trend as it supports JSON exclusively. Below is the full list of Weather APIs in the ProgrammableWeb directory. Not included? Google's secret weather API.