Sri Lanka Weather by Month — Best Time to Visit Each Region

Sri Lanka's climate is set by two monsoons. The Department of Meteorology divides the year into four seasons: the First Inter-monsoon (March–April), the South-West monsoon (May–September), the Second Inter-monsoon (October–November) and the North-East monsoon (December–February). The south-west monsoon drives rain onto the west and south coasts and the central hills; the north-east monsoon drives it onto the east and north. Because they arrive at opposite times, one side of the island is usually dry while the other is wet — the single fact most generic travel guides miss.

This planner turns that system into numbers. It carries the WMO / NOAA 1991–2020climate normals for nine stations, one per climate zone: Colombo, Galle, Kandy, Nuwara Eliya, Anuradhapura, Trincomalee, Batticaloa, Jaffna and Hambantota. For most of these the normals republish the Department of Meteorology's own station records. For your chosen region and month it reads the average monthly rainfall (mm), the average number of rain days, and the mean daytime high and night-time low — a pure table lookup, no interpolation.

It then applies a transparent, stated verdict rule on top of those official averages — clearly a planning heuristic, never a forecast:

• rainfall < 100 mm and ≤ 10 rain days → Great — dry season
• 100–200 mm (or under 100 mm with frequent showers) → Shoulder
• rainfall > 200 mm → Wet — monsoon

Each verdict is tagged with the active Met Department season and a plain reason, such as “the South-West monsoon spares this area.” For coastal regions the tool adds a sea-state note derived from the facing monsoon: the west and south coasts are calm December–April and rough May–September, while the east and north are calm May–September and rough November–February. Finally, a recommender ranks all nine regions by rainfall for your chosen month and traveller focus (beach, hill country or wildlife), so the answer to “where is dry this month?” is one glance away. As an integrity check, the twelve monthly figures for each station sum to its published annual rainfall normal.

• Department of Meteorology, Sri Lanka — Climate of Sri Lanka & live warnings
• Department of Meteorology — the four monsoon/inter-monsoon seasons
• WMO Climate Normals 1991–2020 (NOAA) — station monthly rainfall & temperature

Station normals were last cross-checked on 2026-07-15. Figures are 30-year historical averages (1991–2020), not a forecast; the dry/shoulder/wet verdict is a planning heuristic defined on this page. For a specific date, check the Department of Meteorology's live forecast and warnings before travelling.