This monitoring period covers the planting and overwintering period of winter crops. The national NDVI development profile illustrates initially below average crop condition.

For the whole country, RAIN was 9% below average, temperature (5.5°C) was about average (-0.1°C), while radiation (RADPAR) was 1% below. The Southern Plains, Northwest, and California are the major winter wheat areas of the United States. Dry weather prevailed in the Southern Plains and California: -27% and -30% below average precipitation was experienced for both regions and resulted in -17% and -10% below average BIOMASS. The Northwest experienced  RAIN 3% below the average, temperature 0.4 above the average, while RADPAR was below the average by a significant 7%. 

Dry weather dominated the major winter wheat states. RAIN in Kansas, Oklahoma, Texas, California, and Oregon was 10%, 15%, 32%, and 33% below the average, respectively. Dry weather accelerated the soil moisture loss and will stress winter wheat growth after overwintering. Dry weather (13 to 14% below average) also prevailed in the lower Mississippi, southeast, and southwest.

Dry weather and abnormally low sunshine caused the marked drop in CALF of California and the northwest (-12% and -14%, respectively).  CALF was 10% above the average in the southern plains. NDVI profiles indicated that prevailing dry weather resulted in a significant decline of NDVI below average for the whole country after the middle of January.

Considering the prevailing dry weather and significant decline of CALF in some major winter crops regions, below average crop condition

                                                               (a) Crop phenology of major crops

(a) Crop condition development graph based on NDVI                           (b) Maximum VCI

(c) spatial NDVI patterns compared to 5YA                                             (d) NDVI profiles

(f) Phenology of crops in the United States

Table 3.79. United States agroclimatic indicators by agro-ecological region, current season's values and departure from 15YA, October 2017-January 2018

Table 3.80. United States agronomic indicators by agro-ecological region, current season's values and departure from 5YA, October 2017-January 2018