Blogs
Climate Bulletin for Sri Lanka (Week of 31 October – 07 November 2025)
Highlights
Rainfall Prediction: From 31st Oct-03rd Nov, high rainfall (65-115 mm) is predicted for the Western plains, while Western hills (35-65 mm),Southern plains, Northern Plains, Eastern plains and hills are predicted to receive 0-35 mm of rainfall. From 04th -10th Nov , the rainfall shall intensify further with a similar spatial pattern.
Monitored Rainfall: During 21st-27th October, the average rainfall across Sri Lanka totalled 64 mm which was above–normal. There was much higher rainfall across the Western slopes especially in Ratmalana with a maximum of 109 mm on 24th October.
Monitored and Predicted Wind: From 20th -26th October, winds at 1.5 km height were mostly from the west at speeds ranging 6-10 m/s . From 29th October-04th November, wind speeds are predicted to be moderate, in the range of 1-5 m/s still coming from the West and North West.
Monitored Sea and Land Temperature: Sri Lanka recorded seasonable temperatures across its regions. The Eastern plains were the warmest, with maximum temperature of 32°C , compared to 30°C in the Western plains. The sea surface temperature (SST) was warmer than average around Northern, North Western and Western coasts by 1 – 1.5 °C.
Interpretation
Monitoring
Rainfall: Average Rainfall in the regions for the previous week of (22 October-28 October) = 9.1 mm/day. Maximum Daily Rainfall: 108.5 mm & Minimum Daily Rainfall: 0.0 mm.
Wind: Westerly winds prevailed over the sea area and around the island last week, with wind speeds ranging between 6-10 m/s from 20 – 26 Oct.
Temperatures:During the period 19 – 25 October, Sri Lanka experienced near-neutral conditions except in part of the North Western and North Central provinces.
Prediction
Rainfall: From 28 October– 03 November, rainfall is expected to be 65–115 mm/week in WP region; 35-65 mm/week in WH region; 0 -35mm/week in EP, SP, NP and EH regions.
Temperatures: From 30 October- 12 November, Sri Lanka will experience moderate temperatures, ranging from 17°C to 34°C across the country (Source: SL Met Dept).
Teleconnections: The Madden-Julian-Oscillation (MJO) will slightly suppressed from 27th – 31st Oct, and significantly suppressed from 01st – 10th Nov.
Seasonal Precipitation: The forecast for the October-November-December 2025 season shows high tendency towards the near-neutral tercile.
Terminology for Rainfall Ranges
| Terminology | Rainfall (mm/week) |
| Light Showers | Less than 12.5 mm |
| Light to Moderate | Between 12.5 mm and 25 mm |
| Moderate | Between 25 mm and 50 mm |
| Fairly Heavy | Between 50 mm and 100 mm |
| Heavy | Between 100 mm and 150 mm |
| Very Heavy | More than 150 mm |
