Weather ??, hmmm, wish i could as encouraging !, ok it will be hot, so the heat bit will be ok, aorund 28 to 30 everyday, not much cooler in evening/night time.
You will see some rain, most probably in afternoon/evening time, but don't worry it will not rain all day every day, there will be quite a lot of hot sunny stuff too, bit like we had have had here in London recently :-), there will also be a stiff westerly breeze most of the time too...
Don't forget your sun creams !!, the sun out there is VERY powerful because Sri Lanka is very close to the Equator, your normal 8's 10' ect will not be any use out there !!, minimum 20 is recommened !
If you bump into Chathura or Chat as he likes to be known, (Kuoni rep for that area), please give my regards !, nice guy who has got me out of trouble more than once, and i don't even travel with Kuoni anymore !, he will know me from Ahungalla.