The condition of the US winter wheat crop in major producing states, including top grower Kansas, has tumbled amid reviving drought, which denied seedlings the snow cover to protect them from bitter winter temperatures.
The proportion of winter wheat rated "good" or "excellent" in Kansas has fallen to 35%, from 58% at the end of December, US Department of Agriculture scouts said.
While still significantly better than the 20% of winter wheat rated good or excellent a year ago, when all farms in the state were rated as suffering from drought, the figure is still below the average of 47% at the end of January for the previous five years.
And it represents an unusually sharp decline in condition for a state typically responsible for more than 15% of total US wheat production, and well over 20% of the national winter wheat harvest.
The deterioration came in a period in which all but the western one-third of the state saw "cooler-than-normal" temperatures, the USDA said, in the month which brought the US the so-called polar vortex which brought parts of the country to a standstill.
However, "most of the state saw less than half the normal precipitation", the USDA said.
The proportion of Kansas officially rated as being in drought has risen by 16 points to 63% so far this year, with the rest of the state seen as "abnormally dry".
With snow offering protection to winter crops from colder air temperatures, "farmers in areas with little or no snow cover were concerned with winterkill in their wheat crop," the scouts said.
And crop condition in other central and southern Plains states - like Kansas, producers in particularly of hard red winter wheat - has fallen too.
In Texas, 19% of wheat was rated good or excellent as of Monday, down four points week on week.
The proportion of the Nebraska winter wheat crop rated in the top two condition bands was, at 46%, down 19 points so far this year.
In Nebraska and Texas, drought has spread in 2014 too, albeit more slowly than in Kansas, and covering a smaller area of a little less than one-half of the states.
Indeed, dryness remains in both states well below levels seen a year ago, when the US was recovering from its worst drought in a generation.
However, concerns over further damage to the crops from fresh cold weather expected in the US week have eased with ideas that it will be preceded by snow, offering winter wheat seedlings protection.
"Snow cover has begun to build across the north central and southern Plains and Midwest, and should build further across the central Plains and central Midwest this week," weather service MDA said.
"The increase in snow cover will continue to build winterkill protection for wheat as temperatures remain cold."
Furthermore, it will boost soil moisture too, "and will be most beneficial in the Plains", the weather service said.
At broker Benson Quinn Commodities, Brian Henry said: "The system moving through the southern plains will offer 4-5 inches of snow in western regions and increasing totals as it moves east.
"For many of these regions, increased precipitation in any form is welcome as a better moisture profile would benefit winter wheat that may have been damaged on previous cold snaps.
"Additionally, better snow pack would benefit the crop through the cold snap later this week."
CHS Hedging said: "Snow and forecasted snow in US winter wheat growing regions should reduce winterkill risks, as frigid temperatures once again take over this week."
On the markets, soft red winter wheat, as grown largely in the Midwest, eased 0.2% to $5.62 ½ a bushel in Chicago for March delivery, as of 05:15 local time (11:15 UK time).
Hard red winter wheat for March was 0.2% higher at $6.25 ¾ a bushel in Kansas City.