High-frequency atmospheric variability as stochastic forcing is an important mechanism for ENSO. This presentation summarizes our current knowledge of and remaining challenges to the problem of stochastic forcing of ENSO by westerly wind burst and the MJO. Examples of recent coupled model simulations are given to show the relative importance of westerly wind bursts associated with and independent of the MJO and the physical processes connecting the high-frequency weather phenomena to the interannual variability. Discussions are extended to issues of multiplicative nature of ENSO stochastic forcing and possible benefit of ENSO prediction by including known MJO seasonal and interannual statistics in ENSO prediction models.