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Climate Bulletin for Sri Lanka (Week of 06 – 13 June 2025)
Highlights
Rainfall Prediction: During the next week (04 to 10 June), “moderate” rainfall (25–50 mm) is predicted for the Colombo, Kalutara, Gampaha, Kurunegala, Kegalle, Ratnapura, Kandy, Matale, and Matara districts, while “light showers” rainfall (<12.5 mm) is expected in the Galle, Hambantota, Puttalam, Moneragala, Badulla, Nuwara Eliya, Ampara, Batticaloa, Trincomalee, Polonnaruwa, Anuradhapura, Killinochchi, Mannar, Vavuniya, Mullaitive, and Jaffna districts.
Monitored Rainfall: During the last 8 days (28 May to 04 June), Sri Lanka received an average rainfall of 1.6 mm per day. Most days over the month of May had above-average rainfall levels. Notably, 17th May recorded the highest daily average rainfall of 19 mm/day.
Monitored and Predicted Wind: From May 27 to 02 June, winds at 1.5 km was mostly from the West at speeds ranging between 15-20 m/s. From 05 to 11 June, winds are predicted to come from the North-West, speed ranging between 8-15 m/s.
Monitored Sea and Land Temperature: Average maximum land surface temperature was 31.7 °C in the last week. The Eastern plains were the warmest, followed by the Western and Central plains. The sea surface temperature was around -0.5°C below average , adjacent toMatara district and around 1.0°C above average, adjacent to Eastern province from 27 May to 02 June, 2025.
Interpretation
Monitoring
Rainfall: Most days of May (05 May – 03 June) had above-average rainfall levels. Notably,17thMay recorded the highest daily average rainfall of 19 mm/day.
Wind: Westerly winds prevailed over the sea area and around the is land last week, with wind speeds ranging between 15–20 m/s from 27 May – 02 June.
Temperatures: Temperature anomalies were near-neutral across Sri Lanka from May 25 to 31.
Prediction
Rainfall: During the next week (04 to 10 June), “moderate” rainfall (25–50 mm) is predictedfortheColombo, Kalutara, Gampaha, Kurunegala, Kegalle, Ratnapura, Kandy, Matale, andMataradistricts,while “light showers” rainfall (<12.5 mm) is expected in the Galle, Hambantota, Puttalam,Moneragala, Badulla, Nuwara Eliya, Ampara, Batticaloa, Trincomalee, Polonnaruwa, Anuradhapura,Killinochchi, Mannar, Vavuniya, Mullaitive, and Jaffna districts.
Temperatures: The temperature will remain above normal in some parts of the Northern, Eastern and and Southern provinces, with maximum temperatures reaching up to 37°C of Sri Lanka from 06 to 13 June.
Teleconnections:The MJO will slightly supress from 04 to 08 June, moderately supressrainfallfrom 09 to 13 June, and slightly supress rainfall from 14 to 18 June.
Seasonal Precipitation: The precipitation forecast for the June-July-August 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 |
