There is change in the air for Midwest weather.
For the next four days or so, rains will build in Plains states such as Colorado and Kansas, reaching parts of Nebraska too, "with rainfall amounts of 1-3 inches", WxRisk.com said.
"By Sunday night and Monday, some the rain is room moving into northern Missouri and the southern third of Iowa," the weather service said.
And in the six-to-10 day outlook a "tropical development" in the western area of the Gulf of Mexico "in turn allows for significant moisture to linger over the central and upper Plains as well as all of the western Corn Belt".
While the eastern Corn Belt stays dry, it is the western Corn Belt that a lack of rainfall has been more deeply felt.
'Starting to take a back seat'
But will it come too late to save soybean crops in particular from drought damage?
In the markets, "weather is starting to take a back seat in the world of price discovery as corn and soybean crops head to maturity", Kim Rugel at Benson Quinn Commodities said, noting that soybean harvest was "underway in the south east and expected to start in the north west next week".
Indeed, rains could now begin to threaten harvest progress rather the revive crops.
In fact, yields anyway from the early cut have been better than expected, but this is from areas that enjoyed strong summer rains.
"It will be the yields results out of North Dakota that will be closely watched, as this area came through with an exceptional crop last year, receiving late rains, while this year has been the exact opposite."
'Rather large drop'
So investors had one reason not to react too much to the change in weather.
Another, of course, was the imminence of the US Department of Agriculture's monthly Wasde crop supply and demand report, a key event of the agricultural commodities calendar, due later today.
"Traders appear happy to sit on the sidelines until tonight's Wasde report is released," Luke Mathews at Commonwealth Bank of Australia said.
The big focus is on the extent to which the USDA believes that Midwest heat and dryness has sapped soybean yields, moreso than corn ones, which were seen far enough along in development to have avoided too many deleterious effects.
The expectation is that the USDA will lower its US soybean yield forecast by 1.4 bushels per acre to 42.2 bushels per acre.
But will it?
"This would be a rather large drop in soybean yield", historically, one broker said.
"And the fact that the crop was still rather immature at the time of their data collection may mean the USDA relies more on averages than current soybean data," with averages likely to skew data towards a more positive result.
More on the debate ahead of the Wasde can be found by clicking here.
'Locked and loaded'
And it does matter what result the report comes out with.
"Be mindful that algos are locked and loaded to pounce on potential extremes in US row crop production updates," Richard Feltes at broker RJ O' Brien said.
"Change in US soy production are undoubtedly the most important update, with a US soy yield in excess of 42 bushels per acre viewed as bearish enough to close the top of the $13.31-a-bushel chart gap in Chicago's November futures contract.
"A soybean yield below 40 bushels per acre would spark new November contract highs into the $14.25-a-bushel area."
So, it was not too surprising that investors again proved reluctant to drive prices too far away from last night's closing level, with November soybeans adding 0.1% to $13.60 a bushel as of 09:00 UK time (03:00 Chicago time).
That was a little less the case for corn, for which the Wasde is less sensitive, with Chicago's December lot falling 0.6% to $4.69 ½ a bushel.
In fact, the news on the grain was not all bearish, with some investors taking heart in the rise of 29,000 barrels a day last week in US ethanol production, to 848,000 barrels a week.
"Positive margins and the availability of new crop corn, along with additional capacity returning to the market from seasonal maintenance, should see grind continue to work higher in the weeks ahead," Benson Quinn Commodities said.
However, there was negative news too, with Argentina reportedly indeed raising its cap on corn exports by 3m tonnes, to 20m tonnes, providing more competition for US supplies already looking expensive by global standards.
More on exports will be known later with separate USDA data on US export sales, expected to come in at 400,000-500,000 tonnes for corn (all now 2013-14), and 650,000-800,000 tonnes for soybeans.
Deterioration gone far enough
Corn's decline weighed on wheat too, which lost 0.3% to $6.46 a bushel for December delivery, getting little support either from the wetter turn in the US weather, which is improving prospects for winter wheat sowings.
Not was it helped by rains in Australia, which are improving crop hopes there and depressing prices.
January futures for east coast wheat closed at Aus$275.00 a tonne, down 9.6% so far this month.
"Current forecasts continue to suggest widespread, beneficial rainfall, up to 50mm, for the majority of the east coast grain belt over the coming week," CBA's Luke Mathews noted.
And the Australian, and Argentine, crops matter.
"World numbers will show huge production and adequate supply, but may begin to indicate that trade doesn't want the southern hemisphere crop deteriorating any more than it has," Benson Quinn Commodities said.
US export sales for wheat are expected at 450,000-650,000 tonnes.
Elsewhere, Kuala Lumpur palm oil again tried to put the brakes on its latest losing stream, adding 0.3% to 2,340 ringgit a tonne for November, looking for its first positive close in four sessions.
The contract bounced nicely off its 50-day moving average (on a continuous chart) at to 2,322 ringgit a tonne, and the last of the major moving averages it remains above.
Say Hwa, head of investment at Phillip Futures in Singapore, noted that weaker values have "encouraged bargain-hunting which kept palm oil prices supported".
Still, respected analyst Dorab Mistry cautioned of a sharp drop in palm oil prices as a seasonal rise in output in the major producing states of Indonesia and Malaysia hits the market.
"This new high cycle is just commencing and is likely to give us higher production at least until April 2014," Mr Mistry said.
"It would not surprise me to see new lows in vegetable oil [prices], particularly in palm oil in early January."
Among soft commodities, arabica coffee found itself unable to maintain the positive momentum of the last session, easing 0.2% to 120.55 cents a pound for December delivery.
Indeed, there are still plenty of investors willing to point to the comfortable level of world supplies.
And cotton for December eased 0.3% to 84.10 cents a pound, ahead of a Wasde expected to cut lift the forecast for world production by some 400,000 bales to 117m bales, largely reflecting improvements in India.