Blogs
Climate Bulletin for Sri Lanka (Week of 08 – 15 August 2025)
Highlights
Rainfall Prediction: For 05-11 August, rainfall/week is expected as 15-25 in the Central province 5-15 in the Sabaragamuwa, Southern provinces and Jaffna, Badulla districts 0-5 in the Eastern, North-Central, Western, North-Western provinces and Kilinochchi, Mullaitivu, Mannar, Vavuniya, Moneragala districts.
Monitored Rainfall: During 30 July-4 August, Sri Lanka received an average rainfall of 4 mm/day, while in the hydro catchments, the average rainfall was 6 mm/day. Mattala recorded the highest daily rainfall on 1st August, reaching 99.5 mm.
Monitored and Predicted Wind: From 28 July to 03 August, winds at 1.5 km was mostly from the North-West atspeeds ranging between 10-15 m/s. From 06 – 12 August, wind speeds are predicted to be ranging between 10-15 m/s and expected to come from the North-West.
Monitored Sea and Land Temperature: Average maximum land surface temperature was 31.9 ° C during 30 July to 4 August. The Eastern Plains were the warmest, followed by Southern and Northern Plains. From 28 July-03 August, the sea surface temperature is near-neutral around the Southern coast while it is warmer around the Northern and South-Eastern coasts, ranging between 1.0 °C to 1.5 °C above-average levels.
Interpretation
Monitoring
Rainfall: Average Rainfall in the regions for the previous week of (30 July-8 August) = 3.8 mm/day. Maximum Daily Rainfall: 99.5 mm & Minimum Daily Rainfall: 0.0 mm.
Wind: North-Westerly winds prevailed over the sea area and around the island last week, with wind speeds ranging between 10-15 m/s from 28 July – 3 August.
Temperatures: Temperature anomalies were near-neutral in Sri Lanka from July 27 to August 2.
Prediction
Rainfall: During the next week, 15-25 mm/week rainfall is expected in Central province, while 5-15 mm/week rainfall is predicted for the Sabaragamuwa, Southern provinces and Jaffna, Badulla districts, while 0-5 mm/week rainfall is predicted for the Eastern, North-Central, Western, North-Western provinces and Kilinochchi, Mullaitivu, Mannar, Vavuniya, Moneragala districts.
Temperatures: The temperature will remain above normal in Mullaitivu, Vavuniya, Anuradhapura, Polonnaruwa Trincomalee, Batticaloa, Ampara, Moneragala, Hambantota districts with maximum temperatures reaching between 35°C and 37°C of Sri Lanka from 4-20 August.
Teleconnections: The MJO will be near-neutral from 5 to 9 August, slightly enhance the rainfall from 10 to 14 August, near-neutral from 15 to 19 August.
Seasonal Precipitation: The precipitation forecast for the August-September-October 2025 season shows a 40% of tendancy below normal in the southern half 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 |
