Techniques are described for providing a meeting notification and automatic modification service. A system may be configured to identify an appointment in a calendar application, identify a geographic location of the appointment, and identify, before the appointment time, a geographic location of a first participant of the appointment. Based on the geographic information, the system may identify a route extending from the geographic location of the first participant to the geographic location of the appointment, and may identify a travel time associated with the route. Based on the travel time and the appointment time, the system may determine whether the first participant is estimated to arrive at the appointment on time and, based on the determination, the system may send a message to participants of the appointment or dynamically reschedule the appointment.