Interest in understanding how and why tropical cyclone (TC) activity in various ocean basins is modulated by climate variability has grown substantially over the last four decades. This interest stems from the fact that the TC is one of the most destructive natural catastrophes and causes loss of lives and enormous property damage on a global scale. The large-scale circulation patterns conducive to TC activity during an extreme climate mode differ profoundly from those of an opposite climate mode. In this book, climate modes encompass a suite of time scales, ranging from the shortest ones within a season (90 days) such as the quasi-biweekly oscillation (QBW) and the Madden–Julian Oscillation (MJO), to the interannual variability such as the El Niño-Southern Oscillation (ENSO), North Atlantic Oscillation, and Atlantic and Pacific Meridional Mode, to the multidecadal variability such as the Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation. TC activity includes formation location, frequency of storm occurrence, life span, tracks, landfall rate, and/or storm intensity.