Abstract: The upper wind has a major impact on the safety of the launch vehicle, and the wind speed 3 hours before launching is a determinant for the eventual schedule. If the maximum aerodynamic load generated by the upper wind does not exceed the threshold, the rocket can be launched as planned, otherwise it will be considered to postpone the launch. The deviation of the upper wind 3 hours before and at the launch time should be investigated. Taking the upper wind dataset with an interval of 3.5 hours (December 2014 to December 2020) to analyze the wind difference, and a forecast model for the wind of 0.5 hours after the launch is established using WRF model and the wind data of 3 hours before the launch. It shows that the characteristics of upper wind speed and direction difference within 3.5 hours are related to altitude, season, and the average upper wind speed. Although the maximum wind speed deviation range is -24.00-26.00 m·s^-1, for two-thirds of the cases the deviation is within 10 m·s^-1, which mainly occur in the middle and upper troposphere with altitude of 6.5 km, 11.5 km). The absolute value of the maximum wind direction deviation range is 10.00°-180°, mainly in the 30°, 60°) interval, and this mostly occurs in the middle and lower troposphere with altitude of 1.5 km, 6.5 km). The average absolute deviation of the upper wind speed within 3.5 hours shows an increasing trend with the increase of average upper wind speed 3 hours before the launch, but the relative error and the wind direction deviation decreases, indicating that when the upper wind is strong, the wind direction is less prone to short-term changes. The upper wind deviation within 3.5 hours varies with the seasons, for example, the absolute deviation of winter wind speed is greater than that of summer, but the absolute deviation of wind direction in winter is smaller than that of summer. Using the forecast model results of wind 0.5 hours after the launch can help to avoid the risk of rocket launch in advance.