The atmosphere–ocean system can drive the Earth to produce seismic signals called “microseisms”. These can be produced by large slow-moving storms but also by smaller storms, and in particular small extratropical storms dubbed “weather bombs”, in which the central pressure drops rapidly. Using a seismic array in Japan, Kiwamu Nishida of the University of Tokyo and Ryota Takagi of Tohoku University report both P-wave and previously unobserved S-wave microseisms produced under a weather bomb between Greenland and Iceland. Non-linear forcing of an ocean swell with a 1D Earth model can explain P waves and vertically polarised S waves, but not horizontally polarised S waves. This makes weather bombs a possible new probe of the Earth’s interior.