Sri Lanka monsoon seasons explained — when to visit west coast vs east coast and what to avoid?

This confuses everyone — let me explain it simply.

Sri Lanka has two monsoon systems hitting different coasts:

Yala (south-west) monsoon: May–September
- Affects: West coast (Colombo, Negombo, Bentota, Hikkaduwa, Mirissa, Galle, Unawatuna)
- The south and west get heavy rains during this period
- East coast (Trincomalee, Arugam Bay, Batticaloa) is dry and sunny during this time

Maha (north-east) monsoon: November–February
- Affects: East coast and north (Trincomalee, Arugam Bay, Jaffna, Batticaloa)
- The west and south coast are dry and perfect during this period
- This is peak tourist season for Mirissa, Galle, Hikkaduwa

Is there a time the whole island is bad?
October is the inter-monsoon — transitional rains can affect both coasts simultaneously. Not as bad as full monsoon, but October is the least reliable month island-wide. Avoid if possible.

Your May trip:
May is the start of the south-west monsoon — problematic for Galle, Mirissa, Hikkaduwa. However:
- The Cultural Triangle (Kandy, Sigiriya, Polonnaruwa, Dambulla) is inland and less affected by either monsoon
- The Hill Country (Ella, Nuwara Eliya) has its own micro-climate — May gets afternoon rains but mornings are often fine
- The east coast (Trincomalee, Arugam Bay) is technically going into its shoulder season in May — still surfable, beaches accessible

Practical reality: The monsoon means heavy afternoon rain, not all-day rain. Most tourists do the Cultural Triangle + Hills in May with few problems. I would avoid west coast beaches in May specifically.