Indian Ocean

Wind, swell & tides for Indian Ocean

MADAGASCAR AND THE MASCARENES

The Indian Ocean sits primarily in the Southern Hemisphere, where most of the swells are generated between the Roaring Forties and the Great Southern Ocean located at 60º latitude. These low pressure systems make the journey from the Cape of Good Hope to the SW tip of Australia with year-round regularity, spraying out consistent, quality swell. Madagascar, Réunion, and Mauritius are much closer to the Roaring Forties lows and maintain some sizeable waves, but the SE to S trade winds can spoil the party in winter. Once the NE trades take over in November, it’s time to watch out for cyclones forming in the 15°-25°S latitudes, which usually travel west towards the Mascarene Islands and Madagascar. These swell producers are a real plus, providing powerful swell for the east coasts of all the islands when the southern low pressures are at their weakest. Unfortunately, they are few and far between as well as being accompanied by the onshore NE winds. The SE trades reach maximum intensity from June to October. The anti-clockwise rotation of the Agulhas Current (the world's fastest at 9km/h) keeps Madagascar and the Mascarenes fed with warm water. The Mozambique Channel has 2m+ tides, while heading east sees the semi-diurnal odd tides drop to around 0.5m.

ARABIAN SEA

Swell in this northern hemisphere basin is mainly controlled by the monsoon winds blowing NE from Dec to March, before switching to the SW from May to Oct. The SW monsoon brings the strongest winds to the tropical zone and constant, short-period swell to the Arabian peninsula and the Indian subcontinent. Any Southern Ocean groundswell remnants will be too small to count on and the NE monsoon is not the greatest source for any organised, powerful swell. Major tropical storms also affect the Arabian Sea (May-June and Oct-Nov) meaning there are some waves going unridden in frontier surfing destinations such as Yemen, Oman, Pakistan, Lakshadweep and India. Currents are most notable in the North Indian Ocean because, unlike the Pacific and Atlantic, a seasonal current reversal takes place. This coincides with the monsoon, flowing from the NE towards Africa in winter (Nov-Mar) and then in the opposite direction toward India in the summer months (June-Oct). Called the Somali Current, it follows the wind and can bring slight upwelling to the Horn of Africa region. The Arabian Sea also feeds the warmest sea (the Persian Gulf) and the saltiest sea (the Red Sea).

MALDIVES

The Maldives are perfectly positioned to receive all the Southern Hemisphere groundswell with an unimpeded swell window for anything from the south. However, wave size usually deteriorates as the swells propagate northwards towards the Maldives and the swell often swings a bit to arrive from the SE. Locally generated windswell and occasional cyclone swells add to the inventory, but can't be relied on and the exposed western atolls are usually heavily blown out. While traditional monsoonal periods are stated as Dec-March for the NE and June-Oct for the SW, the actual wind conditions can be divided into three clear periods. The prevailing wind from April to August is SW-W, then from September to November, it swings SW-NW, changing again from December to March, when it predominately blows NW-NE. The currents switch with the seasons but have a negligible effect on water temperatures. Tides are exclusively semi-diurnal odd, and usually less than a metre but spring tides can really move on the atoll passes.

BAY OF BENGAL

The Bay of Bengal fares better than the Arabian Sea when it comes to catching the long-range, southern hemisphere, SW swells that march across the equator in orderly lines. Sri Lanka is first in the firing line, but suffers from the SW onshores during the swell season and prefers a SE-S direction from the mix of wind and groundswells. The SW monsoon swells traverse the east coast of India losing plenty of height as they refract around headlands, before arriving in Myanmar and Thailand with the unavoidable onshore winds. The Andaman Islands suffer the same fate, which leaves a very short season of opportunity in spring when N winds greet early-season swells that have not decayed too much over the long journey. Around 5 cyclones a year wind up in the Bay between April and June then again in September to December, taking a northwards trajectory toward Bangladesh, lighting up the east coast of India along the way. Winds are predictable providing the monsoon sticks to the schedule and drive the oceanic current reversal, but local coastal currents often run in the opposite direction with a series of complex gyres. Expect anything from 0.4m to 3.1m in Thailand.