The subtropics

E. Linacre


You might expect that ‘subtropical’ implies a latitude below that of a Tropic at 23.5 degrees. This is not so. A subtropical climate is widely understood to be just below (sub) that of a tropical climate on a temperature curve.

The term is not well-defined but it implies a range of latitudes between 23.5 and approximately 35 degrees. A subtropical climate implies that the screen temperature normally does not dip below 0ºC. This is a threshold temperature for a wide gamut of plants. This applies to coastal California, southern Florida, coastal Australia, and coastal South Africa, for instance. The poleward limit is higher on the west coast of the northern continents and less on the east, because occasional cold snaps in winter reach further south in the east.

Beyond that the climate is called ‘temperate’, i.e. annual mean temperatures are less than 20ºC whilst the warmest month averages over 10ºC.