It is unpredictable that what can  happen when.
ie if it is very hot in the morning it is very cold in the night for example rajasthan
and we cannot say when it can rain
it will look like it is very hot site but with in minutes it will start raining
actually this is the reason most of the farmers go in loss because they start farming thinking that it will rain less but it will rain a lot and the whole crops will get spoiled