Blogs
Climate Bulletin for Sri Lanka (Week of 18 July to 25 July 2025)
Highlights
Rainfall Prediction: For 15-21 July, rainfall/week is expected as 55-65 in the Western Prov. 35-55 in the North Western, Central, Sabaragamuwa Prov, and Galle, Matara, Jaffna, Kilinochchi, Mullaitivu, Vavuniya, Trincomalee districts. 25-35 in the Uva, North Central Prov and Hambantota, Batticaloa, Ampara, Mannar districts.
Monitored Rainfall: In the first half of July, Sri Lanka only received 6 mm of rainfall, even though the average rainfall for July is around 21 mm. •During July 8-15, Sri Lanka received an average rainfall of 0.6 mm/day, while in the hydro catchments, the average rainfall was 6 mm/day.
Monitored and Predicted Wind: From July 7 to 13, winds at 1.5 km were mostly from the North-West at speeds ranging between 10-15 m/s. Monitored Land & Sea Temp From 16-22 July, wind speeds are predicted to increase slightly, ranging between 10-20 m/s and expected to come from the North West.
Monitored Sea and Land Temperature: The average maximum land surface temperature was 33.1 °C during 8-15 July. •The Eastern Plains were the warmest, followed by the Southern and Northern Plains. From 7 to 13 July, the sea surface temperature is near neutral around the Southern coast, while it is warmer around the Eastern, Western, and North-Eastern coasts.
Interpretation
Monitoring
Rainfall: There was a drastic rainfall decline in the first half of July, receiving only 6 mm compared to the normal rainfall level of 21 mm. This condition indicates a potential drough condition in Sri Lanka during this period.
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 7-13 July.
Temperatures :Temperature anomalies were warmer in Sri Lanka except for the Northern, North Central, North-Western provinces, and some parts in Uva and Eastern provinces from July 6 to 12.
Prediction
Rainfall: During the next week, 55-65 mm/week rainfall is expected in the Western province, while 35-55 mm/week rainfall is predicted for the North-Western, Central, Sabaragamuwa provinces and Galle, Matara, Jaffna, Kilinochchi, Mullaitivu, Vavuniya, Trincomalee districts, while 25-35 mm/week rainfall is predicted for the Uva, North-Central provinces and Hambanthota, Batticaloa, Ampara, Mannar districts.
Temperatures: The temperature will remain above normal in some parts of the Eastern, Uva and Southern provinces, with maximum temperatures reaching between 34°C and 36°C of Sri Lanka from 17-25 July.
Teleconnections: The MJO will be near neutral from 15 to 19 July, slightly suppress the rainfall from 20 to 24 July, moderately suppress the rainfall from 24 to 29 July.
Seasonal Precipitation: The precipitation forecast for the August-September-October 2025 season shows a 40% of tendancy below normal in Southern, Western, Central, Uva and Sabaragamuwa provinces 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 |
