The Quasi-Biennial Oscillation (QBO) affects how the Madden-Julian Oscillation (MJO) influences weather patterns in the North Pacific. During a westerly QBO winter, MJO phase 6–7 has stronger effects compared to an easterly QBO winter. This is because the MJO phases before 6–7 have opposite effects in the two QBO phases, leading to interference that weakens the MJO's impact during an easterly QBO winter. Prediction models show better accuracy for MJO phase 6–7 during a westerly QBO winter. This means that more MJO activity during an easterly QBO winter doesn't necessarily mean stronger MJO effects in the North Pacific.