Sri Lanka enjoys a perennial hot temperature due to its tropical location on the map. The monthly averages lie between 72 °F (22 °C) and 92 °F (33 °C) in the lowlands. The monthly average temperature of Central Highlands falls between 44 °F (7 °C) and 71 °F (21.6 °C). This lower temperature is attributed to the higher altitudes
The climate of Sri Lanka is not the same throughout the year, it changes every day and seasonally as well and rainfall is the cause of such variation in climate. Sri Lanka can be divided into two zones – Wet Zone and Dry Zone and what zone an area belongs to is decided by the amount of rain that zone receives, its variability, and effectiveness.
The Wet Zone, comprising the southwestern region of the island, witnesses heavy rainfall with annual averages ranging from 98 inches along the coast to more than 150 inches in the highlands, and the rainfall is seasonally well distributed. Thus, soil moisture and surface drainage are maintained throughout the year. A greater part of the rain to the Wet Zone comes from the southwest monsoon from May to September.
Over the dry zone, the annual rainfall ranges from 30 to 70 inches in the different areas most of it being received during the northeast monsoon season from November to January.