After school activities may or may not be cancelled if it is raining, depending on the severity of the rain, the location of the activities, and the policies of the school or organization that runs the activities.
For example, if the rain is light and the activities are held indoors, they may still go on as scheduled. However, if the rain is heavy or there is lightning and thunder, outdoor activities will likely be cancelled for safety reasons.
Additionally, some schools or organizations may have policies that automatically cancel after school activities if there is rain, regardless of the severity. It is always best to check with the school or organization that runs the activities to find out if they will be held as scheduled.