Rainfall significantly influences climatic conditions and agricultural productivity, particularly in arid ecosystems dependent on rainfed agriculture. This study analyzes monsoon precipitation and its extreme events at an intraseasonal scale over the past four decades (1981-2021) in the Western Plains (WP) and Kachchh Peninsula (KP) Agroecological Region (WKAER) of India. It further evaluates how the intraseasonal variability of monsoon extremes impacts Kharif crops in this region. Gridded precipitation datasets from the India Meteorological Department (IMD) (0.25 degrees x 0.25 degrees) and crop productivity data from the Directorate of Economics and Statistics, Ministry of Agriculture and Farmers Welfare, Government of India, were utilized. Trends from 1981 to 2021 were analyzed for each month (June-September) and the entire monsoon season (JJAS) using widely used Mann-Kendall (MK), Sen Slope Estimator, and Innovative Trend Analysis (ITA). The ITA was specifically applied to analyze extreme rainfall trends as the Sen Slope shows ineffective in these instances. Moreover, the correlation between rainfall extremes and crop productivity (bajra, cotton, groundnut, moong) was examined using Spearman's rank correlation. Results indicate increased rainfall during June (0.402 mm a-1), August (1.161 mm a-1), September (0.615 mm a-1), and the overall monsoon season (1.940 mm a-1), with spatial variations captured through grid-wise analysis across WKAER. Moreover, the rainfall and its extremes have notably risen for almost all observed months over the KP. A positive trend was observed in June, September, and for the whole monsoon season in WP, except in central and southwestern WP. The rainfall in July declined throughout WP, contrasting with eastern and northeastern WP. During August, northern WP experienced a decline in rainfall, while the rest of the WP exhibited increasing rainfall trends, with the trend's magnitude intensifying towards the south. The study highlights the dominance of intraseasonal extremes in shaping regional rainfall patterns, with varying impacts on Kharif crop productivity. Notably, a low positive correlation exists between monsoon rainfall and crop productivity, with negative correlations observed in Jhunjhunu and Kachchh during August. The results underscore the potential for targeted interventions to enhance agricultural outputs in response to favorable monsoon variations in arid regions, supporting economic strategies for sustainable livelihood improvement.