What is claimed is:1. A monitoring system that is configured to monitor a property, the monitoring system comprising:one or more sensors that are located at the property and that are configured to generate sensor data; andone or more monitoring devices that are configured to:receive the sensor data;analyze the sensor data;based on the analysis of the sensor data, determine that a person has left the property and is likely going to an additional property; andbased on the determination that the person has left the property and is likely going to the additional property, perform an action related to an additional monitoring system that is configured to monitor the additional property.2. The system of claim 1, wherein the one or more monitoring devices are configured to perform the action related to the additional monitoring system that is configured to monitor the additional property by transmitting, to the additional monitoring system, an instruction for the additional monitoring system to prepare the additional property for the person.3. The system of claim 2, wherein the one or more monitoring devices are configured to:determine at least one environmental condition of the property before the person left the property; andtransmit an instruction for the additional monitoring system to prepare the additional property for the person by transmitting an instruction for the additional monitoring system to change at least one environmental condition of the additional property to match the at least one environmental condition of the property.4. The system of claim 3, wherein the at least one environmental condition includes at least one of an ambient temperature, music playing, or lighting style.5. The system of claim 1, wherein the one or more monitoring devices are configured to determine that the person has left the property and is likely going to the additional property by:determining that the monitoring system received an instruction to arm within a predetermined time range; anddetermining that a person exited the property during the predetermined time range.6. The system of claim 1, wherein the one or more monitoring devices are configured to:receive data indicating traffic conditions;determine that the person is likely going to arrive at the additional property after an expected arrival time based on the data indicating the traffic conditions; andperform the action related to the additional monitoring system that is configured to monitor the additional property by transmitting an instruction for the additional monitoring system to output a notification indicating that the person is likely going to arrive at the additional property after the expected arrival time.7. The system of claim 1, wherein the one or more monitoring devices are configured to:determine that sensor data indicates that a particular person is likely at the property,determine that sensor data indicates that the particular person is likely at the additional property; andbased on the conflicting determinations that the particular person is likely at the property and the additional property, provide, for output, data indicating a security event at the property or the additional property.8. The system of claim 1, wherein the one or more monitoring devices are configured to determine that the person has left the property and is likely going to the additional property by:determining a confidence score that indicates a likelihood that the person has left the property and is likely going to the additional property;comparing the confidence score to a confidence threshold;based on comparing the confidence score to the confidence threshold, determining that the confidence score satisfies the confidence threshold; anddetermining that the person has left the property and is likely going to the additional property based on the determination that the confidence score satisfies the confidence threshold.9. The system of claim 1, wherein the one or more monitoring devices comprise a monitoring server.10. The system of claim 1, wherein the one or more monitoring devices comprise a controller located at the property and a monitoring server located remote from the property.11. A computer-implemented method, comprising:receiving sensor data sensed by one or more sensors of a monitoring system that is configured to monitor a property;analyzing, by one or more monitoring devices associated with the monitoring system, the sensor data;based on the analysis of the sensor data, determining, by the one or more monitoring devices associated with the monitoring system, that a person has left the property and is likely going to an additional property; andbased on the determination that the person has left the property and is likely going to the additional property, performing, by the one or more monitoring devices associated with the monitoring system, an action related to an additional monitoring system that is configured to monitor the additional property.12. The method of claim 11, wherein performing the action related to the additional monitoring system that is configured to monitor the additional property comprises transmitting, to the additional monitoring system, an instruction for the additional monitoring system to prepare the additional property for the person.13. The method of claim 12, wherein transmitting, to the additional monitoring system, the instruction for the additional monitoring system to prepare the additional property for the person comprises:determining at least one environmental condition of the property before the person left the property; andtransmitting an instruction for the additional monitoring system to change at least one additional environmental condition of the additional property to match the at least one environmental condition of the property.14. The method of claim 13, wherein the at least one environmental condition includes at least one of an ambient temperature, music playing, or lighting style.15. The method of claim 11, wherein determining that the person has left the property and is likely going to the additional property comprises:determining that the monitoring system received an instruction to arm within a predetermined time range; anddetermining that a person exited the property during the predetermined time range.16. The method of claim 11, further comprising:receiving data indicating traffic conditions; anddetermining that the person is likely going to arrive at the additional property after an expected arrival time based on the data indicating the traffic conditions,wherein performing the action related to the additional monitoring system that is configured to monitor the additional property comprises transmitting an instruction for the additional monitoring system to output a notification indicating that the person is likely going to arrive at the additional property after the expected arrival time.17. The method of claim 11, further comprising:determining that sensor data indicates that a particular person is likely at the property,determining that sensor data indicates that the particular person is likely at the additional property; andbased on the conflicting determinations that the particular person is likely at the property and the additional property, provide, for output, data indicating a security event at the property or the additional property.18. The method of claim 11, wherein determining that the person has left the property and is likely going to the additional property comprises:determining a confidence score that indicates a likelihood that the person has left the property and is likely going to the additional property;comparing the confidence score to a confidence threshold;based on comparing the confidence score to the confidence threshold, determining that the confidence score satisfies the confidence threshold; anddetermining that the person has left the property and is likely going to the additional property based on the determination that the confidence score satisfies the confidence threshold.19. The method of claim 11, wherein the one or more monitoring devices comprise a monitoring server.20. The method of claim 11, wherein the one or more monitoring devices comprise a controller located at the property and a monitoring server located remote from the property.