National Volcano Early Warning and Monitoring System Act (Sec. 3) This bill directs the United States Geological Survey (USGS) to establish the National Volcano Early Warning and Monitoring System to monitor, issue warnings of, and protect U.S. citizens from undue and avoidable harm from, volcanic activity. The purposes of the system are to: (1) organize, modernize, standardize, and stabilize the monitoring systems of U.S. volcano observatories; and (2) unify such systems into a single interoperative system. The objective of the system is to monitor all U.S. volcanoes at a level commensurate with the threat posed by the volcanoes by: (1) upgrading existing networks on monitored volcanoes, (2) installing new networks on unmonitored volcanoes, and (3) employing geodetic and other components when applicable. The system shall include: (1) a national volcano watch office that is operational 24 hours a day and 7 days a week, (2) a national volcano data center, (3) an external grants program to support research in volcano monitoring science and technology, and (4) modernization activities including the comprehensive application of emerging technologies. The USGS must: (1) submit to Congress a five-year management plan for establishing and operating the system, and (2) establish an advisory committee to assist in implementing the system. The USGS may enter into cooperative agreements designating institutions of higher education and state or territorial agencies as volcano observatory partners for the system. The USGS must conduct a study to assess the feasibility of establishing volcano observatories in Guam, the Northern Mariana Islands, and American Samoa to monitor volcanic activity across the western and southern Pacific Ocean along the Ring of Fire. If determined to be feasible, the USGS may enter into cooperative agreements with institutions of higher education or territorial agencies to establish such observatories as part of the National Volcano Early Warning and Monitoring System.