Why is it said that "Monsoon wind is known for its uncertainties"? Explain any fours reasons

Why is it said that “Monsoon wind is known for its uncertainties”? Explain any fours reasons.

Monsoon wind is known for its uncertainties because
(i) The movement of low-pressure trough controls the spatial distribution of rainfall.
(ii) The alteration of wet and dry spells varies in intensity, frequency and duration.
(iii) It sometime causes heavy floods in one part, it may be responsible for drought in other.
(iv) It is often irregular in its arrival and retreat.