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Climate Bulletin for Sri Lanka (Week of 27 June – 03 July, 2026)
Highlights
Predictions
The US NOAA Climate Prediction Center predicts that rainfall will decrease across Sri Lanka during 23–29 June compared to the previous week. The Western Plains and Southern Plains are expected to receive 45–65 mm of rainfall during this period. From 24–30 June, winds are forecast to blow from the southwest and northwest at speeds of 8–15 m/s.
ElNiño Event
As of mid-June, the Pacific Ocean has transitioned into El Niño conditions. Sea surface temperatures in the equatorial Pacific (Niño 3.4 region) are currently around 1.1°C above average. Some parts of the Indian Peninsula are experiencing drier-than-normal conditions, which is a typical seasonal impact of El Niño. However, parts of western and northeastern India are expected to receive heavy rainfall over the next two weeks. The Indian Ocean is currently behaving differently from a typical El Niño pattern, with warmer-than-normal sea surface temperatures. Meanwhile, western regions of Sri Lanka are expected to receive more than 45 mm of rainfall, which is typical for June.
Monitoring
Compared to the first week of June, which experienced relatively dry conditions, Sri Lanka received above-average rainfall during 11–22 June. During 17–23 June, the average daily rainfall was 3 mm. Ratmalana recorded the highest daily rainfall, receiving 54 mm on 21 June, while Ratnapura received 50 mm on 22 June. From 15–21 June 2026, winds at an elevation of 1.5 km were predominantly from the northwest, with speeds ranging from 8 to 10 m/s. Overall, temperatures across Sri Lanka remained typical for June. The Eastern Plains recorded an average maximum temperature of 34.9°C, while the Eastern Hills recorded an average minimum temperature of 18.9°C.
Rainfall Prediction
Rainfall is expected to decrease across Sri Lanka during 23–29 June compared to the previous week. The Western Plains and Southern Plains are forecast to receive 45–65 mm of rainfall. The Western Hills and Eastern Hills are expected to receive 25–45 mm, while the Northern Plains and Eastern Plains are likely to receive 5–25 mm. Rainfall is expected to decrease further during 30 June–6 July. The Western Plains and Southern Plains are forecast to receive 15–55 mm of rainfall, while the rest of Sri Lanka is expected to receive 5–15 mm.
Source: NOAA CPC
Monitored Rainfall
During 17–23 June, the average daily rainfall across Sri Lanka was 3 mm. Compared to the first two weeks of June, which experienced relatively dry conditions (1–6 mm of rainfall), much wetter conditions (6–16 mm) were observed across the country during 17–22 June. Ratmalana recorded the highest daily rainfall, receiving 54 mm on 21 June, while Ratnapura received 50 mm on 22 June.
Monitored Land & Sea Temperature
During 17–23 June, the maximum average temperature across Sri Lanka was 31.7°C, slightly lower than the previous week’s average of 32.0°C. The Western Hills recorded the lowest average temperature at 26.6°C. Sea surface temperatures around Sri Lanka remained about 1.0°C above average along the southwest coast, while temperatures were slightly below average along the northeast coast.
Monitored & Predicted Wind
During 17–23 June, the maximum average temperature across Sri Lanka was 31.7°C, slightly lower than the previous week’s average of 32.0°C. The Western Hills recorded the lowest average temperature at 26.6°C. Sea surface temperatures around Sri Lanka remained about 1.0°C above average along the southwest coast, while temperatures were slightly below average along the northeast coast.
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 |
