Highlights

Predictions: From 9-11 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 45-85 mm. From 10 -16 June, wind speeds are predicted to be 10-20 m/s from the Southwest and Northwest.
 
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: Compared to the month of May which experienced double the amount of rainfall than expected, relatively dry conditions were observed across SL during 1-12 June. During This period, the average daily rainfall was 4 mm. The highest daily rainfall was in Kurunegala – 42mm on 6 June and Ratnapura – 35 mm on 5 June. From 1 – 7 June 2026, winds at 1.5 km elevation were mostly from the West at 10 – 15 m/s. Overall the temperature was typical for June across SL. The Eastern Plains had an average maximum temperature of 35.4°C. The Eastern Hills had an average minimum temperature of 20.5°C.
 

Rainfall Prediction: From 9 – 15 June, rainfall is predicted to decrease throughout SL: 45-85 mm is predicted for the Southern Plains, Western Hills & Plains; 25-45 mm is predicted for the Eastern Hills & Plains; 15-25 mm for the Northern Plains. From 16-22 June, rainfall shall increase: 55-95 mm is predicted for the Southern Plains, Western Hills & Plains; 25-55 mm is predicted for the Northern Plains, Eastern Hills & Plains. (Source: NOAA CPC)

Monitored Rainfall: Compared to the month of May which experienced double the amount of rainfall than expected, relatively dry conditions were observed across SL during 1-12 June. The highest daily rainfall was in Kurunegala – 42mm on 6 June and Ratnapura – 35mm on 5 June. During 3-9 June, the average daily rainfall was 4 mm.

Monitored Land & Sea Temperature: During 3-9 June, maximum average temp in SL was 32.1°C, lower compared to the previous week – 32.1°C. Western Hills had the lowest temperatures – 26.6°C. The sea surface temperature around SL was above the seasonal average by 0.25°C – 0.5° C around Southern coasts and by 0.5°C – 1.5°C around other coasts of SL.

 

Monitored & Predicted Wind: From 1 – 7 June 2026, winds at 1.5 km elevation were mostly from the West at 10 – 15 m/s. From 10 – 16 June 2026, winds are predicted to speed up ( 10-20 m/s from the Southwest and Northwest).



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