Brazil rainfall from late September through November was well below average as it was in many Argentina locations. The lack of precipitation in both countries occurred at about the same time it was realized that Brazil had run out of old crop soybeans to sell. The combined impact sent futures market prices soaring.

However, after a 30-day delay South America’s long-awaited monsoon flow pattern finally initialized in the first week of December, bringing enhanced rainfall and relief to weeks of below-average precipitation. The weather change brings back a more normal rainfall pattern that should support soybeans in center west and center south Brazil while maintaining concern over La Niña-based dryness in eastern Argentina, far southern Brazil, southern Paraguay and Uruguay.

Typically, in La Niña years, monsoonal rainfall is delayed in Brazil for a brief period of time from late September into much of October with seasonal precipitation evolving in November. This year — for the first time in this meteorologist’s 41 years of forecasting in Brazil — the monsoonal rains were delayed a full month longer. The delay resulted in unprecedented dryness from late September through November, causing delayed planting, early-season crop moisture stress and raising speculation over poor yielding summer crops.

Production cuts already have been confirmed from early planted corn and soybean fields in Brazil and in some early corn and sunseed areas in Argentina where a drought problem of its own was underway. Argentina’s drought began during the autumn wheat planting season and it still has not let go even though there has been a few brief bouts of rain recently.

Most of the production cuts occurring so far in South America have probably not had a big impact on the bottom line for 2021 production because of increased soybean area planted in Brazil. However, if the turnaround in monsoonal precipitation proves to be temporary there will be much more to chat about later this month and in January.

World Weather, Inc. notes that Brazil typically receives far more rain than it needs for the best yielding soybeans and other summer crops. Timely rainfall that is lighter than usual does not necessary translate into poor yielding crops. It depends on how well the rain is distributed and when it occurs. This year’s rain distribution has been mostly good for crop development, although the low soil moisture present in much of the nation in recent weeks has threatened to reduce yields in several areas.

The increased monsoonal rainfall that has occurred recently will see to it that crops suffering from moisture stress in November and early December get timely rainfall that will support aggressive crop development ahead of reproduction. Experience from similar situations in the United States suggests the most important part of the summer growing season is from flowering to pod filling and production can still be quite successful if rain occurs during this period of crop development despite a restricted rainfall pattern in the early weeks of the growing season.

The next few weeks will have much to say about production potentials. A good distribution of timely rain could seriously turn around this year’s crop to support another record or near-record production year. However, that would most likely be accomplished because of increased area planted and not because of ideal growing conditions. World Weather, Inc. believes some yield and production cut already has occurred this year, but the increased area planted should help to balance out the losses and keep production looking relatively good. With that said, World Weather, Inc. does not believe production will be much better than 130 million tonnes, but an assessment of the recent heat and moisture stress will have to be completed in the next few weeks to better determine production changes.

In the meantime, Argentina’s struggle with dryness remains and it is not likely to change much through December with southern and east-central parts of the nation to be most negatively impacted by ongoing lighter-than-usual precipitation.

Southern Brazil grain and oilseed production areas recently have experienced some timely rainfall after dryness earlier this season was serious enough to already write down early season planted corn production potential.

Southern and far northeastern Brazil will not be included in the more favorable rain expected over the balance of December from center west through center south production areas. Production in the south likely will be a little light because of anticipated La Niña-biased dryness that will come and go through the summer season. Northeastern Brazil — which is drying out now — will get some timely rainfall a little later this summer after a short-term bout of drying through mid-December.

The bottom line is not a bad one for Brazil, which is still expected to yield well despite all of the early season dryness. Argentina losses may be a little more significant in the southeast along with parts of Uruguay and southern Paraguay, although it is too soon to accurately predict production given the erratic nature of rainfall for the next few weeks.

In the meantime, World Weather, Inc. is still waving a caution flag on the next few years of worldwide grain and oilseed production. Drought in the western half of North America is unlikely to completely go away in the next few months, bringing the region to spring with ongoing dryness. The potential remains great for some lingering La Niña biases to remain during the Northern Hemisphere spring and especially the summer. Those biases may not bode well for long-term dryness relief and there is a good chance some of the spring and summer will be drier and warmer than usual. Such conditions could exacerbate the already dry environment in North America, raising the potential for additional dryness expansion during the heart of the 2021 growing season. A negatively phased Pacific Decadal Oscillation is also possible during 2021, which also may contribute to some warmer- and drier-biased conditions during the summer.

Nothing is set in stone, but with all that already has occurred in 2020 and that expected in 2021 still points to the expanding dryness potential that often can and does occur in the post solar minimum years. Persistent La Niña conditions can breed dryness issues just like negative PDO and the presence of drought in many areas. Much of this can also be said of parts of central Asia as well, but that is another story.