This bill requires the Department of Homeland Security (DHS) to develop and conduct an exercise to enhance collective domestic preparedness for and response to a terrorist attack during an extreme cold weather event (e.g., an event caused by a polar vortex when Arctic air expands southward). The scenario in the exercise must involve a terrorist attack causing cascading effects on critical infrastructure (i.e., systems and assets of vital importance to national security, public health, or safety) and must address how public and private entities can coordinate to mitigate such effects and bolster community resilience. Within 60 days after completion of the exercise, DHS must submit to Congress an after-action report including the initial findings of the exercise, plans for incorporating lessons learned into future operations, and any proposed legislative changes.