The question of when is the best time to visit Sri Lanka doesn’t have a straightforward answer as one may think. For a small island, Sri Lanka has quite a complicated weather system as it is affected by two separate monsoon seasons. The main southwest monsoon brings rain to the west and southwest coasts and hill country from May to September (wettest from May to June). The less severe northeast monsoon hits the north and eastern coasts from October to January (wettest from November to December).
This means that there is always good weather in some part of the country at any given time. In most simplified terms the best time to visit the west and south coasts and hill country is from December to April, while the best weather on the north and east coast is from April/May to September.
The good news is Sri Lanka is blessed with a tropical climate with temperatures in the high 20s or low 30s most of the year. Watch out for that humidity though! Relative humidity in Sri Lanka typically ranges from 60% – 90% and is generally higher in the south-west and hill country. This means packing those light-weight cotton clothing is a must.
The period from December to mid-April is considered the peak season for best overall weather and therefore overall visitor numbers. However, there are also benefits to travelling outside of this period, with the shoulder season often providing the best of both worlds; great weather and a lower visitor numbers.
So the best time to visit Sri Lanka can really be anytime, provided you take into account which side of the island to focus on any given month. Sri Lanka really is a year-round holiday destination so pack those bags and chase the sun!