<p>Clouds play a crucial role in modulating surface solar radiation, particularly in tropical coastal regions influenced by monsoon and cyclonic systems. This study investigates the impact of maritime cloud types and their microphysical characteristics on surface shortwave radiation over Nagapattinam, Tamil Nadu, India, during June–December 2024. Ground-based observations were integrated with satellite datasets to analyze cloud properties and estimate Short-Wave Cloud Radiative Forcing (SWCRF) across contrasting monsoon regimes. Radiative effects of clouds were evaluated using cloud base height and optical depth to classify them. Results indicate that low- and mid-level clouds - notably stratocumulus and cumulus - account for most of the radiative forcing. These clouds produce a peak instantaneous SWCRF values reaching − 310 w/m². Cirrus clouds (high level) which are often observed in association with cyclones generate less forcing (-20 to -50&#xa0;W/m²). Also, diurnal variability indicates that both cloud optical depth and liquid water path have their maximum at local noon, as a result producing the greatest attenuation of solar radiation. Statistical analysis reveals strong nonlinear relationships between SWCRF and cloud optical depth (<i>R</i> = − 0.86) and liquid water path (<i>R</i> = − 0.82), while effective radius shows a weaker influence. These findings provide process-level insights into cloud–radiation interactions, though limited to shortwave effects and a single-season dataset.</p>