The weather averages 27c and only gets chilly in the mountains. In the south where Talalla Retreat is located the temperature rarely rises above 35c.
There are two distinct monsoon seasons – in the Northeast, the season runs from is December to March and in the Southwest from May to October. However, whilst the rain is regular and plentiful it only lasts for an hour or so each day so the monsoon is actually quite a pleasant time to be here.
The good news is that southern Sri Lanka is enjoyable to visitors all year round. Even monsoon times are blue-sky days with a spectacular evening thunderstorm. For many this is the most exciting time of the year. The driest times of the year are between November-April. Overall, Sri Lanka is a year round destination, the south especially so.http://www.tourism-srilanka.com/best-time.html