Revised India monsoon outlook

We are almost two months into the 2021 monsoon in India, so it's time to take a look at the state of the monsoon. A prolonged break period in the monsoon from mid-June into July brought the all India rainfall departure from +10% of normal on 30 June down to more than 5% below normal in early July.

Courtesy of the IMD

As of 28 July, all India rainfall stands at 2% below normal, so it's close to normal for India as a whole. However, if we look at rainfall by regions and states, we can see there are some noticeably dry areas through the first half of the season. The most noticeable areas are in far northeastern India as well as Gujarat and parts of Rajasthan. Odisha and Kerala are also running sizable deficits despite a few monsoon lows impacting Odisha and even some flash flooding in parts of Kerala earlier in July.

Courtesy of the IMD

In the nearer term, a monsoon low over Bangladesh will enhance rain in Odisha, West Bengal, northeastern India, Bangladesh and portions of Nepal into Friday. Enhanced rain from the low is expected to reach Uttar Pradesh and Madhya Pradesh this weekend with some rain possibly reaching eastern Rajasthan and eastern Gujarat early next week.

Looking ahead, there are signs that there could be another break period for parts of northwestern and north-central India starting the week of 9 August. This break period does not look to be as long-lasting as the one in late June and early July, but would certainly hinder making up rainfall deficits in some areas. This break period in northwestern India around the second week of August could mean an increase in rainfall over northeastern India and parts of southern India which may help chip away at deficits in these areas. There are signs that better rains could return to southwestern and central India late in August heading into early September.

One factor we are continuing to watch is the negative Indian Ocean Dipole (-IOD) that was declared underway by Australia's Bureau of Meteorology. The -IOD is weak but can strengthen some over the next month or so with the -IOD expected to carry well into boreal autumn. The development of a -IOD has us concerned that rainfall could be less than our forecast from April.

Courtesy APEC Climate Center

Several seasonal models continue to look wet for August and September, but their track record this season has been to be too wet in many areas. As a result, we believe the climate models are likely too wet in most areas during August and September. The ECMWF and CFS weeklies that go out into early September are not nearly as wet as these models are showing.

Taking into account the current state of rainfall in India, all the modeling and teleconnections, we have decided to revise our monsoon forecast. Below is the revised monsoon forecast for India.

An area of concern is Odisha which could be drier than forecast while above-normal rainfall could reach farther north across Maharashtra to near Mumbai, especially if wet weather returns in late August.