The coast and lowlands are hot and humid all year.
The interior highlands are milder and drier, but can become
freezing between December and February. Rainfall is scarce throughout most of the country.
The climate of Mexico varies according to altitude.
The low-lying coastal areas are typically tropical,
hot and humid, but the weather in Mexico City, which is
sited at an altitude of 2,300 metres above sea level, is far
more moderate. Mexico City has pleasant summers and mild winters,
with an annual average temperature of 64 °F (18 °C). Seasonal variations
in temperature are small, but May is the warmest month of the year, and
January the coldest, when night frosts are possible. Mexico City has a high
average annual rainfall, most falling in summer, the wettest month being July,
and the driest month February.
For an idea of weather conditions visit the following site