The west coast region of California, Oregon, and Washington is beginning to green up as a result of winter rains. The coastal region of Oregon and Washington is always green because of Douglas-fir forests. While most of the vegetation is still dormant in the northern part of the conterminous United States in March, the vegetation in the coastal regions of the Pacific northwest and the southeast continues to green up. The annual grasslands in California are at the peak of green. In April, the winter wheat region of central Kansas and Oklahoma can be easily distinguished because of its dramatic contrast with the surrounding region.
Snow cover remains in the high mountain regions.
By May, the wheat growing region of central Oklahoma and Kansas is at the peak of green. The greenness of grasslands and forests contrasts with the Cornbelt region of Illinois, Iowa, Ohio, and Minnesota. Here cultivation and early planting result in low indications of vegetation. Brown areas in the northern Mississippi Basin are indicative of bare soil as corn and soybean fields are prepared for planting. The peak of green occurs in the southeastern coastal region in June.