In climatology, the term megathermal (or less commonly, macrothermal; from Ancient Greek mégas 'large', makrós 'tall', thermós 'warm, hot') is sometimes used as a synonym for tropical.
In order for a particular place to qualify as having a megathermal climate, every single month out of the year must have an average temperature of 18 °C or above.
It ranges from southeast Asia and most of India to the most northern regions of Australia as well as southern parts of Mexico and Florida, nearly all of Central America and most of Brazil.
An arid type prevails to some of northern Africa, while in the center of the continent and in parts of Madagascar the climate stays humid.
In addition, what temperature fluctuations do exist in an equatorial climate will typically bear no relationship to the astronomical seasons for the applicable side of the equator, while in the (outer) tropical subtype the temperature will move in concert with the seasons, the time of higher sun and longer days being warmest and the time of lower sun and shorter days coolest.