Systems and methods for scheduling appointment reminders are based on multiple conditions including estimated travel time. An estimate of the time needed to travel between the user's location and the location of the appointment can be determined by retrieving location information from a global address list (GAL), a local address book of a calendaring application, from a map service, or other location determining technology. Users can subscribe to alert service to receive information regarding recent events such as traffic problems, flight delays, weather conditions, etc., which is then used in setting or modifying reminder times. Notifications can be generated for timing conflicts based on the estimated travel time. If the estimated travel time would require the user to leave a previous appointment early, or be late for a subsequent appointment, a notification can be generated to the user.