Winter wheat (Triticum aestivum L.) is grown in the southern Great Plains as a single crop for cattle (Bos taurus L.) forage plus grain for milling. Wheat planted for grazing plus grain in Oklahoma often receives 112 kg N/ha for a grain yield of 3360 kg/ha plus 90 kg N/ha for a 3000 kg/ha forage yield. More than 50% of this N is applied in the fall before planting. Wheat is considered an excellent forage, but excessive nitrate accumulation in juvenile wheat can pose risks to ruminants. Yearly and spatial differences of nitrate in wheat forage were related to differences in soil properties and climatic conditions to identify factors posing nitrate risks. Two adjacent transects in a 2 ha wheat pasture were systematically sampled yearly (2001-2004) at the onset of fall grazing. For the sample locations, overall yearly mean±SE (n=48) for forage nitrate-N ranged from 580±40 to 6580±140 g/kg, while biomass ranged from 1200±60 to 3960±140 kg/ha and total N from 39.7±0.4 to 47.2±0.2 g/kg. Within years forage nitrate was nearly always significantly correlated with biomass (0.39 to 0.70), total N concentration (0.37 to 0.69), soil nitrate (0.39 to 0.48), and available N (0.30 to 0.62), but not with soil pH, available P, exchangeable Al, soil total C and N, and pasture elevation. Among the soil traits measured at the onset of grazing, soil nitrate to a 25-cm depth appears to offer some promise as a predictor of forage nitrate. Yearly forage nitrate was strongly correlated with growing degree days (0.90) and rainfall (0.99) 10-d-before grazing and with season-long total solar radiation (0.74). Forage nitrate (and other traits) exhibited spatial differences, but these differences were small relative to yearly differences. Fall climatic conditions linked to abundant forage biomass signal possible nitrate risk and warrant testing the wheat forage for nitrate.