Blogs
Climate Bulletin for Sri Lanka (Week of 09 January – 16 January 2025)
Highlights
Rainfall Prediction: From 06th-12th Jan 2026, heavy rainfall (105-135 mm) is predicted for the Northern Plains and Eastern Plains; fairly heavy rainfall (65-105mm) is predicted for the Western Plains and Hills, Eastern Hills and Southern plains. From 13th- 19th Jan , the rainfall shall decrease across SL. Western Plains and Southern Plains will receive moderate rainfall (45-55 mm).
Monitored Rainfall: During 31st December-6th January, the average rainfall across Sri Lanka totaled 48 mm. There was fairly heavy rainfall across the Eastern Plains and Eastern Hills, especially in Pottuvil with a maximum of 76 mm on 5th January.
Monitored and Predicted Wind: From 29th Dec 2025-04th Jan 2026, winds at 1.5 km height were mostly from the northeast at speeds ranging 8-10 m/s. From 08th-14th Jan2026, wind speeds are predicted to be in the range of 4-10 m/s coming from the North East.
Monitored Sea and Land Temperature: Seasonable temperature was recorded. The Southern plains had the maximum temp of 31.2°C, while the Eastern Hills had the minimum temperature of 23.4 °C. The sea surface temperature around Northern and Southern coasts, was slightly below average, ranging between 0.5°C and 0.25°C.
Interpretation
Monitoring: Average Rainfall in the regions for the previous week of (31 December 2025 – 06 January 2026) = 6.8 mm/day. Maximum Daily Rainfall: 75.6 mm & Minimum Daily Rainfall: 0.0 mm.
Rainfall: From 31 December – 06 January, most days experienced below-average rainfall levels. The highest daily rainfall was recorded on 31 December as 28 mm/day.
Wind :North-Easterly winds prevailed over the sea area and around the island last week, with wind speeds ranging between 8-10 m/s from 29 Dec 2025 – 04 Jan 2026.
Prediction
Rainfall: Rainfall: From 06 – 12 January 2026, rainfall is expected to be 105–135 mm/week in NP, EP regions; 65-105 mm/week in WH, EH ,SP, WP regions.
Temperatures: Temperatures: From 08 – 14 January, temperature will remain normal for Sri Lanka. (Source: SL Met Dept).
Teleconnections: The Madden-Julian-Oscillation (MJO) will slightly suppress the rainfall from 06th-10th Jan 2026 and will be near-neutral from 11th – 20th Jan 2026.
Seasonal Rainfall Prediction: The forecast for the January-February-March 2026 season shows high tendency towards the near-neutral tercile for the southern half while it shows higher tendency towards 45% above-normal tercile for the northern half of Sri Lanka.
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 |
