Outdoor activities involve being outdoors! Many activities are weather-dependent. This means some won't take place if for example, there is rain, or if there is no snow or too much (or too few) waves, etc. The weather conditions will be specific to each activity.
Only the instructor has the final call when it comes to cancelling or maintaining an activity. The instructor will reach out to you to let you know (unless indicated otherwise in your confirmation email). If you are unsure, please feel free to contact the instructor directly. If they do need to cancel, they will then try to reschedule the activity with you. If a reschedule is not possible, you will be entitled to a full refund, as per Adrenaline Hunter's