It is hot, tropical and at times wet, but you are guaranteed sun most days.
When it’s hottest
From March to the end of May it can get swelteringly hot, and we mean sweltering.
When it’s coolest
From September to February . The heat picks up from March peaking in April/May. June and July are also warm and pleasant
When it’s wettest
Colombo’s monsoon hit from May to August typically (this is the Southwest monsoon). These months have unpredictable weather. Mid-October to early November is rainy with a monsoon of sorts taking place. In December it tends to rain in the evenings, from December to around February is the Northwest monsoon but most rain falls east of Sri Lanka’s central mountains.
- Dehydration is a concern during April & May. Make sure to drink plenty of water and obviously, Thambilis, which are incredible for rehydration, you can also get rehydration salts from pharmacies, the best local rehydration salt being a concoction called Jeewanee (soluble sachets). They are revolting but think of the health benefits, alternatively bring over from your home country.
- Sri Lankans are not well-adapted to rain, given the amount of sunshine year-round. Rain makes traffic in Colombo chaos. Any workers will be guaranteed to be late and you will forever be told that you are ill because of the rain.