Monsoon rainfall is one of the major contributors to the water resources in Bangladesh. Considering this importance, this study was carried out to observe the spatiotemporal pattern of monsoon rainfall. Daily rainfall and prevailing wind speed for the period of 1986 to 2015 (April to November) of Dinajpur, Bangladesh were collected and analyzed in order to identify the trend, shifting pattern, and the past and probabilistic future arrival and withdrawal dates for 1 year out of 4, 10, and 25 years. It was revealed that the arrival and withdrawal dates were fluctuating between May to June and August to November, respectively. Besides, the mean arrival and withdrawal dates were evident on 3 June and 27 September, respectively and most of the dates were in the defined range of June to September. The early arrival dates were between 1 53 days except in 1992 (30 days later) and the late withdrawal dates were between 1 69 days except in 1987 and 2009 (5 and 10 days earlier). Finally, it was saliently appeared that the probabilistic early (21 May, 9 May and 30 April) and late (12 June, 29 June and 8 July) arrival dates are depicting the overall early start of monsoon, whilst the probabilistic early (13 September, 1 September and 23 August) and late (10 October, 22 October and 1 November) withdrawal dates are representing the delayed overall withdrawal of monsoon rainfall in the targeted domain.
Key words: Monsoon rainfall, Arrival dates, Withdrawal dates, Shifting, North-western Bangladesh, Climate change
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