Media Center
Climate Bulletin for Sri Lanka (Week of 09 – 16 May 2025)
Highlights
Rainfall Prediction: During the next week (07 May 13 May), “fairly heavy” rainfall (50–100 mm) is predicted for the Central, Western, Sabaragamuwa, and Uva while “moderate” rainfall (25-50 mm) is expected in the Southern, and North-Western provinces. “Light showers” are expected in the Eastern, North-Central and Northern provinces.
Monitored Rainfall: During the last 8 days (April 27 – May 04), Sri Lanka received an average rainfall of 9.1 mm per day, while the hydro catchment areas recorded an average of 10.8 mm per day. Highest daily rainfall was in Maha Illuppallama on 27th April (77.6 mm).
Monitored and Predicted Wind: From April 29 to May 05, winds at 850 mb (1.5 km) from the South-West at speeds ranging between 3 – 6 m/s. From May 08 to May 14, Westerly to Southwesterly winds are expected, with wind speeds ranging from 4 to 8 m/s.
Monitored Sea and Land Temperature: Average maximum land surface temperature was 32.4°C in the last week. The Northern plains were the warmest, followed by the Eastern and Western plains. The sea surface temperature around Sri Lanka ranged between 0.25°C – 1.°C above average from 29 April to 05 May 2025.
Interpretation
Monitoring
Rainfall: Average Rainfall in the Met Stations for the previous week of (27 April – 04 May) = 9.1 mm/day. Maximum Daily Rainfall: 77.6 mm & Minimum Daily Rainfall: 0.0 mm.
Wind: South-Westerly winds prevailed over the sea area and around the island last week, with wind speeds ranging between 3–6 m/s from 29 April – 05 May.
Temperatures: Temperature anomalies were near-neutral across Sri Lanka from April 27 to May 03.
Prediction
Rainfall: During the next week (07 May 13 May), “fairly heavy” rainfall (50–100 mm) is predicted for the Central, Western, Sabaragamuwa, and Uva while “moderate” rainfall (25-50 mm) is expected in the Southern, and North-Western provinces. “Light showers” are expected in the Eastern, North-Central and Northern provinces.
Temperatures: From May 08 to May 14, maximum temperatures will range from 25°C to 30°C in some parts of the Central and Sabaragamuwa provinces, while other parts of Sri Lanka will experience the maximum temperature between 30°C and 35°C.
Teleconnections: The MJO will neutral rainfall from May 06 to May 15, and moderately suppress rainfall from May 16 to 20 May.
Seasonal Precipitation: The precipitation forecast for the May–June–July 2025 season shows a 40% or more tendency toward above normal precipitation of Sri Lanka.
Terminology for Rainfall Ranges
| Terminology | Rainfall (mm/week) |
| Light Showers | Less than 12.5 mm |
| Light to Moderate | Between 12.5 mm and 25 mm |
| Moderate | Between 25 mm and 50 mm |
| Fairly Heavy | Between 50 mm and 100 mm |
| Heavy | Between 100 mm and 150 mm |
| Very Heavy | More than 150 mm |
