I think i can give some good information ,
but i'll put a disclaimer right away that i'm biased as i currently manage the kite center in Srilankakite
Sri Lanka is slowly getting developed for kiting and there is loads of it still generally undiscovered.
The wind has a massive venturi effect between India and Sri Lanka and blows strong all summer !
Season starts around May 1 every year and will continue to around October 10.
May and June are strong, and wind is on every day ! most guys are using 8-9m kites now and girls on 6-7m kites.
July the winds start getting a bit lighter slowly and continue this trend untill the end of the season.
By the time august comes i occasionally bring out the 12m , but will still spend the large majority of my sessions on 8m or 10m (75kg )
If you look on the forecasts, windguru and windy are quite accurate here and you'll find 17-25 knots winds on average for the summer with some days going up stronger than that.
In terms of spots there are 3 different ones established at the moment.
1) Kappalady lagoon
First disovered flatwater lagoon in Sri Lanka, used to be a fresh water lagoon but since the dune broke this may it became brackish water.
Smallest and shallowest of the lagoons but can handle up to about 20 kites.
You can ride in the ocean as well but at own risk.
About 2h30-2h45 from the airport by van.
There are some different camps around the lagoon or in the village next to it.
2) Kalpitya lagoon
The biggest lagoon , its about 1,5km by 700m and has most of the schools coming to kite on it. Some camps are in the village , others are by the lagoon or entrance channel so you can have all locations depending on your personal preference.
The lagoon has shallow areas on the side , but the majority is about 1,5-2m deep so deep enough to crash safely and also to foil if you wish.
I work in Srilankakite which has its camp set up right at the lagoon side , you can launch your kite at 20m from the rooms and kite right at the lagoon.
The camp is complete with rental , school , shop , professional kite repair , sports masseur , sunset rooftop bar and yoga to keep you kiting as much as you want or chill in between !
Accommodations are all full board service so you don't need to worry about going shopping in the village and cooking by yourself.
Accomodations vary greatly on budget but we got everything from teepees to a villa with swimming pool.
There are a bunch of spots in the vicinity as well to do downwinders in flat water or in waves,
As well as the best flatwater spot i've ever ridden just 1h by boat away which is a 2km offshore sand bar with perfect wind , sun and flat water deep enough to train safely around waist to shoulder, we do daytrips and overnight safaris there and its well worth saving a bit of your budget to go there multiple times as the spot is really world class !
www.srilankakite.com
https://www.facebook.com/Srilankakite/
Kalpitiya is around 3h from the airport
3) Mannar
New and upcoming kitespot in Adams bridge ( old land connection to India )
Has a lot of small islands which will give some nice flatwater, but you have to be carefull with the water depth.
there is one camp with native wooden structures, and one camp currently in construction which should be ready for soft opening by July.
Travel time from the airport is around 6h.
Almost all kite places will be camp style which will offer you a full board service as it really makes your life a lot easier
so you don't have to go shopping in the wet market and cook by yourself, also the local restaurants can be a bit too spicy for the western taste.
For the rest the country has amazing scenery , both on the water and trips inland to take a break from kiting every once in a while.
I'm really enjoying my time here and recommend it as there is great riding to be done here in nice warm waters !