Highlights

Predictions: From 2-8 June, the US NOAA Climate Prediction Center predicts that the rainfall shall decrease across SL. During this period, Southern Plains, Western Plains & Hills are predicted to receive rainfall of 65-95 mm. From 3 -9 June, wind speeds are predicted to be 10-20 m/s from the Southwest and West. El Niño Event: As of mid-May, the equatorial Pacific is rapidly
 
ElNiño Event: As of mid-May, the equatorial Pacific is rapidly transitioning into El Niño conditions. El Niño is a natural climate pattern that occurs when ocean waters in the central and eastern Pacific become warmer than usual, affecting weather around the world. Currently, sea surface temperatures across equatorial Pacific are around 0.5–2.0°C above average, indicating a strengthening shift toward El Niño conditions. However, the Indian Ocean is currently behaving differently from what is typically expected during an El Niño event, with warmer-than-normal sea surface temperatures, active rainfall, and wind patterns.
 
Monitoring: During the month of May, SL received nearly double the expected rainfall. However, relatively dry conditions were observed across the country during 27 May – 2 June. During This period, the average daily rainfall was 2 mm. The highest daily rainfall was in Bandarawela – 47 mm and Galle – 24 mm on 28 May. From 25 – 31 May 2026, winds at 1.5 km elevation were mostly from the West at 10 – 15 m/s. Overall the temperature was typical for May across SL. The Northern Plains had an average maximum temperature of 33.2°C. The Western Hills had an average minimum temperature of 18.6°C.
 

Rainfall Prediction: From 2 – 8 June, rainfall is predicted to decrease throughout SL: 65-95 mm is predicted for the Southern Plains, Western Hills & Plains; 25-65 mm is predicted for the Northern Plains, Eastern Hills & Plains. From 9 – 15 June, rainfall shall remain same: 65-95 mm is predicted for the Southern Plains, Western Hills & Plains; 25-65 mm is predicted for the Northern Plains, Eastern Hills & Plains. (Source: NOAA CPC)

Monitored Rainfall: During the month of May, SL received nearly double the expected rainfall. However, relatively dry conditions were observed across the country during 27 May -2 June. The highest daily rainfall was in Bandarawela – 47 mm and Galle – 24 mm on 28 May. During 27 May – 2 June, the average daily rainfall was 2 mm.

Monitored Land & Sea Temperature: During 27 May – 2 June, maximum average temp in SL was 32.3°C, higher compared to the previous week – 32.0°C. Western Hills had the lowest temperatures – 27.9°C. The sea surface temperature around SL was above the seasonal average by 0.5°C – 1.5°C around Western and Eastern coasts; below the seasonal average by 0.5°C – 1°C around other coasts of SL.

 

Monitored & Predicted Wind: From 25 – 31 May 2026, winds at 1.5 km elevation were mostly from the West at 10 – 15 m/s. From 3 – 9 June 2026, winds are predicted to speed up ( 10-20 m/s from the Southwest and West).



Terminology for Rainfall Ranges

TerminologyRainfall (mm/week)
Light ShowersLess than 12.5 mm
Light to ModerateBetween 12.5 mm and 25 mm
ModerateBetween 25 mm and 50 mm
Fairly HeavyBetween 50 mm and 100 mm
HeavyBetween 100 mm and 150 mm
Very HeavyMore than 150 mm