subtropical arid subtropical An arid subtropical condition is a subtropical condition in which an environmental system has an annual average temperature near 18.2 degrees Celsius with their coldest month averaging between 2 and 13 degrees Celsius, the absence of regular rainfall, and high humidity. Mild variants are generally located in areas adjacent to powerful cold ocean currents. ORCID:0000-0002-4366-3088 desert climate semi-arid climate semi-desert climate