March is the last full month of the north-east monsoon and often the pick of the three. The swell is unchanged, the mornings are still offshore, and the season crowd thins as the European winter ends. From April the monsoon turns and this coast loses the wind that makes it work.
What changes is the heat. March into April is the hottest stretch of the Sri Lankan year and the sea follows it to 29°C, and the honest consequence is about duration rather than comfort. On a cold coast a session ends when you start shivering, which is usually well before you have stopped wanting to surf. Here it ends when your arms do. On a run of long, mellow reef waves that difference is the whole trip: you get three or four times as many waves in a week, and the waves are what you came for.
Two coasts in the world are at their own peak in March, and the other one is Colombia. Its reef at Pico de Loro is a genuinely extraordinary wave, sixteen clean days in thirty, and you reach it by flying forty minutes from Medellín to a jungle strip and continuing by boat, and its beginner rating is the lowest there is. March at 29°C with a school in the bay and a reef ten minutes away is the other kind of trip entirely.
If you are choosing on the wave, base yourself at Ahangama. The Rock is a reef peak breaking both ways several hundred metres off Kabalana beach, so what looks rideable from the sand is not what is rideable from the peak, and it works at any tide. If you are choosing on the week, Hiriketiya is an hour and a half east: a horseshoe cove three hundred metres across that holds a wave on the days the open beaches close out, and lanes, flip-flops and early nights around it.

