Everything You Need to Know About Sea Conditions in the South China Sea

The South China Sea has a predominately tropical climate, dictated by two monsoons that are characterised by their direction of airflow.


The Northeast monsoon is active in the winter months of November to March, while during the summer between May and September the Southwest monsoon is active. The controlling factor of these monsoons is the intertropical convergence zone (ITCZ) between the North-east trade winds in the northern hemisphere (NH) and the south-east trades in the southern. During mid-summer in the NH, the convergence zone sits across mainland China but gradually moves southwards, reaching its southern limit of northern Australia by winter. The transition between each monsoon period is associated with light winds, but frequent thunderstorms as the ITCZ moves over.


Why is the region essential for the offshore industry?


The South China Sea is strategically important, with approximately one-third of the world's shipping passes through it (carrying an estimated $3 trillion in trade each year). It also contains lucrative fisheries, which are crucial for the food security of millions in Southeast Asia.


Alongside this, huge oil and gas reserves are believed to lie beneath its seabed. Estimates of the size of these oil and gas reserves in the South China Sea dramatically vary. Regardless, it’s becoming increasingly important that the area is strategically important for countries based in the region.


Why is it vital to understand sea conditions?


Accurate and precise weather forecasts are a necessity in most offshore operations to reduce costs, mitigate or avoid delays and improve safety.


When operational limits are marginal, understanding the sea conditions through accurate forecasts are essential (and often required by insurers). Short to medium term forecasts (5-7 days) help with day to day running, ensuring operational limits and the safety of personnel/equipment are within bounds. Further Outlook Forecasts (15 days) give project managers, stakeholders, and decision-makers a better idea of upcoming weather events and help them mitigate potential delays.


Understanding sea conditions in the South China Sea and Southeast Asia region


To help offshore companies understand the specific weather conditions in key regions around the world, we've created The Offshore Sea Conditions Guides. It's our six-part series, explaining the key characteristics of sea conditions around the world. Each edition explores how specific conditions affect offshore operations, and what you can do to minimize the impact of these conditions on your next project.


The South China Sea and Southeast Asia guide includes insight on key weather phenomenon in the region, including:

  • Monsoon Climate
  • Sumatras
  • Typhoons


Want to learn more? Download your copy now


Download The Offshore Sea Conditions Guides