Blogs
Climate Bulletin for Sri Lanka (Week of 28 November – 05 December 2025)
Highlights
Rainfall Prediction: From 25th Nov – 01st Dec, heavy rainfall (>135 mm) is predicted for the entire country. On 29th and 30th Nov, significant rainfall is expected in Sri Lanka, particularly over the Western plains and hills, and the Northern plains. From 02nd – 08th Dec, the rainfall shall decrease further.
Monitored Rainfall: During 18th – 24th November, the average rainfall across Sri Lanka totalled 136 mm. There was higher rainfall across the Northern plains and Eastern plains especially, with Jaffna recording 99mm on 23rd November and Pottuvil receiving 99 mm on 25th November.
Monitored and Predicted Wind: From 17th -23rd Nov, winds at 1.5 km height were mostly from the northeast and east at speeds ranging 3-8 m/s. From 26th Nov-02nd Dec, wind speeds are predicted to be in the range of 3-8 m/s coming from the North and North West.
Monitored Sea and Land Temperature: Sri Lanka recorded seasonable temp across its regions. The Southern and Western plains were the warmest, with maximum temp of 30.9°C. The sea surface temp was warmer than average around Sri Lanka, ranging between 0.3°C and 1°C above average.
Interpretation
Monitoring
Rainfall: Average Rainfall in the regions for the previous week of (19-25 November) = 19.4 mm/day. Maximum Daily Rainfall: 99.4 mm & Minimum Daily Rainfall: 0.0 mm.
Wind: North-Easterly and Easterly winds prevailed over the sea area and around the island last week, with wind speeds ranging between 3-8 m/s from 17 – 23 Nov.
Temperatures: During the period 9 – 15 Nov, Sri Lanka experienced near-neutral conditions except in some parts in Sabaragamuwa and central provinces.
Prediction
Rainfall: From 25 November – 01 December, rainfall is expected to be above 135 mm/week in Sri Lanka.
Temperatures: From 27 – 29 November temperature will remain below normal for Central province. From 30 November – 10 December, temperature will remain normal for Sri Lanka. (Source: SL Met Dept).
Teleconnections: The Madden-Julian-Oscillation (MJO) will significantly suppress from 24th Nov – 08th Dec.
Seasonal Precipitation: The forecast for the December-January-February 2026 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 |
