What atmospheric condition would cause a rocket launch to be canceled?

Winds greater than 30 km/h can significantly impact the safety and stability of a rocket launch. High winds can lead to difficulties in rocket tracking, control, and stability during ascent. Additionally, strong winds can cause the rocket to drift off course, increasing the risk of it landing in an unintended area, potentially affecting people and property on the ground. Wind shear, or the change in wind speed and direction at different altitudes, can also pose dangers during the rocket's flight. Therefore, launching in high winds is generally considered risky and may necessitate the cancellation of the launch.

Visibility greater than 5 km is typically not a concern for rocket launches, as this is generally considered good visibility. A temperature below 0°C, while possibly affecting materials and performance, does not inherently lead to canceling a launch unless other conditions are present. Rain showers may impact certain equipment or tracking systems but do not automatically necessitate a launch cancellation if safety measures can be implemented.