Highlights

Predictions

From 21-27 July, the US NOAA Climate Prediction Center predicts that the overall rainfall across Sri Lanka shall remain  similar to the previous week (0-25 mm). During this period, Western Hills, Western, Southern & Eastern Plains are predicted to receive rainfall of 15-25 mm. From 22-28 July, wind speeds are predicted to be 4-8 m/s from the Northwest and 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 1.2°C above average. Many parts of the Indian Peninsula are experiencing below-normal rainfall patterns, consistent with the typical seasonal influence of ongoing El Niño conditions. However, Northeastern India is expected to receive  heavy rainfall in the next two weeks. The Tropical Indian Ocean sea surface temperatures currently differs from a typical El Niño influence. According to CCSR/IRI Multi-Model Probability Forecast, Sri Lanka is expected to receive much heavier rainfall than usual from August onwards. The likelihood increases from 45% during August-October to 70% during September-November. This unusually wet weather is caused by the El Niño influence.

Monitoring 

From 11 – 20 July, SL received below-average rainfall (1-2 mm) than typical for July. During 15-21 July, the average daily rainfall was 0.2 mm. The highest daily rainfall was in Colombo – 5 mm & Ratmalana – 4.5 mm on 20 July. From 13-19 July 2026, winds at 1.5 km elevation were mostly from the Northwest at 8 – 15 m/s. Overall the temperature was typical for July across  Sri Lanka. The Eastern Plains had an average maximum temperature of 35.7°C. The Eastern Hills had an average minimum temperature of 17.7°C.

Rainfall Prediction

From 21 – 27 July, rainfall is predicted to remain similar to the last week throughout SL: 15-25 mm is predicted for the Western Hills, Western, Southern & Eastern Plains, 0-15 mm is predicted for the Eastern Hills & Western Plains. From 28 Jul – 3 Aug, rainfall shall increase : 45-75 mm is predicted for the Western Hills, Western & Southern Plains; 15-45 mm is predicted for the rest of Sri Lanka.

(Source: NOAA,CPC)

Monitored Rainfall

During 15-21 July, the average daily rainfall across Sri Lanka was 0.2 mm. From 11- 20 July, Sri Lanka received below-average rainfall (1-2 mm) than typical for July. During 15-21 July, the highest daily rainfall was in Colombo – 5 mm & Ratmalana – 4.5 mm on 20 July. In the regions outside the western slopes and hills there was little rainfall as is typical for July.

Monitored Land & Sea Temperature

During 15-21 July, average maximum temp in Sri Lanka was 32.4°C, lower compared to the previous week- 32.7°C. The Eastern Plains was warmest- 35.7°C. The sea surface temperature around Sri Lanka was warmer by 1.5°C around northern, eastern and western coasts and cooler around northeastern coasts.

Monitored & Predicted Wind

From 13–19 July 2026, winds at 1.5 km elevation were mostly from the Northwest at speeds of 8 – 15 m/s. From 22–28 July 2026, winds are predicted to slow down to 4-8 m/s and arrive from the Northwest and Southwest. 

Source: NOAA Climate Prediction Centre.