Highlights

Monitoring

Monitoring: Rainfall: Sri Lanka was relatively dry from 10-31 Aug with daily rainfall averaged over the island ranging from 1-5 mm. During 26 Aug – 1 Sep, the average daily rainfall across SL was 2 mm. The highest daily rainfall was in Ratnapura – 33 mm on 1 Sep and Galle – 31 mm on 26 Aug. Wind: From 24-30 Aug 2026, winds at a height of 1.5 km were mostly from the Northwest at 10-15 m/s. Temperature: Several cities of Eastern and Northern Plains had extremely high maximum temperatures exceeding 35°C. Polonnaruwa had the highest temperature of 39.2°C on 01 September and 38.4°C on 31 August. The Eastern Plains had an average maximum temperature of 36.0°C & Western Plains had an average maximum temperature of 31.1°C. The Eastern Hills had an average minimum temperature of 19.4°C.

Predictions

Rainfall: From 1-7 Sep: the US NOAA Climate Prediction Center predicts that the average rainfall across SL shall range from 0-65 mm. During this period: Eastern Plains are predicted to receive rainfall of 45-65 mm; Eastern Hills are predicted to receive 25-45 mm; Western Hills and Northern, Eastern, Western Plains are predicted to receive 0-25 mm. According to CCSR/IRI Multi-Model Probability prediction, there is a 50% likelihood of SL receiving higher-than-normal rainfall during September-November, increasing to 60% during October-December.Wind: From 2-8 Sep, wind speeds are predicted to be 4-8 m/s from the Northwest & Southwest.

El Niño Event

El Niño conditions continue to prevail across the equatorial Pacific Ocean (Niño 3.4 region). Currently, sea surface temperature in the Niño 3.4 region are around 2.7°C above average. Meanwhile, the Dipole Mode Index (DMI) is at +0.11°C, indicating neutral IOD (Indian Ocean Dipole) conditions – a positive dipole event is identified at DMI = 0.4. According to IRI climate forecasts, there is about a 80-90% possibility of a positive IOD conditions from September through December 2026.

Rainfall Prediction

From 1–7 Sep, 45–65 mm is predicted for the Eastern Plains; 25–45 mm is predicted for the Eastern Hills; 0–25 mm is predicted for the Western Hills and Northern, Western & Eastern Plains. From 8–14 Sep, 45–65 mm is predicted for the Eastern Plains; 0–45 mm is predicted for the rest of SL. 

(Source: NOAA CPC)

Monitored Rainfall

SL experienced a relatively dry period from 10–31 Aug, with daily rainfall averaged over the island ranging from 1–5 mm. During 26 Aug–1 Sep, the average daily rainfall across SL was 2 mm. Highest daily rainfall was recorded in Ratnapura – 33 mm on 1 Sep and Galle – 31 mm on 26 Aug.

Monitored Land & Sea Temperature

During 26 Aug–1 Sep, average maximum temperature in SL was 32.4°C, similar to the previous week (32.4°C). The Eastern Plains was the warmest, at 36.0°C. The sea surface temperature around SL was warmer by 1.5°C around the northern, eastern and western coasts, and by 1.0°C around the rest of the coasts.

Monitored & Predicted Wind

Wind speeds are predicted to decrease in September compared with August (8–15 m/s), marking the end of the kite-flying season. From 24–30 Aug 2026, winds at 1.5 km elevation were mostly from the Northwest, at speeds of 10–15 m/s. From 2–8 Sep 2026, winds are predicted to slow down to 4–8 m/s and arrive from the Northwest & Southwest.