What is the appropriate climate for a coffee plant? In the tropics I know that coffee requires some elevation, but increasingly coffee is being grown in the subtropics.  What are the necessary and sufficient conditions for growing coffee?
I found this website which prescribes the following subtropic and equatorial growing conditions.


  The subtropical regions, at high altitudes of 16-24° (Illy, 21). 
  Rainy and dry seasons must be well defined, and altitude must be
  between 1800-3600 feet.  These conditions result in one coffee growing
  season and one maturation season, usually in the coldest part of
  autumn.  Mexico, Jamaica, the S. Paulo and Minas Gerais regions in
  Brazil, and Zimbabwe are examples of areas with these climate
  conditions (Illy, 21).
  
  The equatorial regions at latitudes lower than 10° and altitudes of
  3600-6300 feet (Illy, 21).  Frequent rainfall causes almost continuous
  flowering, which results in two coffee harvesting seasons.  The period
  of highest rainfall determines the main harvesting period, while the
  period of least rainfall determines the second harvest season. Because
  rainfall is too frequent for patio drying to occur,  artificial drying
  with mechanical dryers is performed in this type of coffee growing
  environment. Examples of countries that have this climate are Kenya,
  Colombia, and Ethiopia (Illy, 21).