Complex sentence: It affects the Indian subcontinent, where it is one of the oldest and most anticipated weather phenomena and an economically important pattern every year from June through September, but it is only partly understood and notoriously difficult to predict.
Split into simpler sentences: It affects the Indian subcontinent, where it is one of the oldest and most anticipated weather phenomena and an economically important pattern every year from June through September. Yet it is only partly understood and notoriously difficult to predict.