A smoking article (1 101 201 301) comprises: a combustible heat source (10) having opposed front (12) and rear (14) faces one or more airflow channels (16) extending from the front face (12) to the rear face (14) of the combustible heat source (10) an aerosol forming substrate (30) downstream of the rear face (14) of the combustible heat source (10) and a thermostatic bimetal valve (20 120 220 320) located between the rear face (14) of the combustible heat source (10) and the aerosol forming substrate (30). The thermostatic bimetal valve (20 120 220 320) is arranged to deform from a first position in which the valve (20 120 220 320) substantially prevents or inhibits fluid communication between the one or more airflow channels (16) and the aerosol forming substrate (30) to a second position in which the one or more airflow channels (16) and the aerosol forming substrate (30) are in fluid communication when the thermostatic bimetal valve (20 120 220 320) is heated to above a threshold temperature.
