Highlights

Monitoring

Rainfall: SL received above average rainfall (for September) from 1-9 Sep, with daily rainfall averages ranging from 4-9 mm. During 2-8 Sep, the average daily rainfall across SL was 1.5 mm. The highest daily rainfalls was at Bandarawela on 3 Sep (71 mm) and at Ratmalana on 6 Sep (17 mm ). Wind: From 31 Aug – 6 Sep 2026, winds at 1.5 km elevation were mostly from the Northwest and West at speeds of 8 – 10 m/s. Temperature: Several cities of Eastern and Northern Plains had extremly high maximum temperatures exceeding 35°C. Polonnaruwa had the highest temperature of 38.7°C on 4 September and 38.6°C on 6 September. The warmest regions were: Eastern Plains with an average maximum temperature of 36.3°C & Western Plains with an average maximum temperature of 32.1°C. The coldest region was: The Eastern Hills had an average minimum temperature of 19.7°C.

Predictions

Rainfall: From 8-14 Sep, the US NOAA Climate Prediction Center predicts that the average rainfall across SL shall range from 15-85 mm. During this period, Southern and Western Plains are predicted to receive rainfall of 55-85 mm; Eastern and Western Hills are predicted to receive 35-55 mm; Northern and Eastern Plains are predicted to receive 15-35 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 9-16 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 (SST) in the Niño 3.4 region are 2.7°C above average. Indian Ocean (IO) SST: The IO Dipole Mode Index (DMI) is at +0.11°C, indicating neutral IO Dipole conditions. Positive dipole event is identified at DMI = 0.4. According to CCSR/IRI climate forecasts, there is 80-90% possibility of a positive IOD from September through December 2026.

Rainfall Prediction

From 8-14 Sep, 55-85 mm is predicted for the Southern and Western Plains; 35-55 mm is predicted for the Eastern and Western Hills; 15-35 mm is predicted for the Northern and Eastern Plains. From 15-21 Sep, 55-85 mm is predicted for the Eastern and Western Plains; 0-55 mm is predicted for the rest of SL.

(Source: NOAA CPC)

Monitored Rainfall

SL experienced above-normal rainfall levels from 1-9 Sep, with daily rainfall averaged over the island ranging from 4-9 mm. During 2-8 Sep, the average daily rainfall across SL was 1.5 mm. The highest daily rainfall was recorded in Bandarawela – 71 mm on 3 Sep, followed by Ratmalana – 17 mm on 6 Sep.

Monitored Land & Sea Temperature

During 2-8 Sep, average maximum temperature in SL was 33.2°C, higher than the previous week (32.4°C). The Eastern Plains was the warmest, at 36.3°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

From 31 Aug-6 Sep 2026, winds at 1.5 km elevation were mostly from the Northwest and West, at speeds of 8-10 m/s. From 9-16 Sep 2026, winds are predicted to slow down to 4-8 m/s and arrive from the Northwest & Southwest.