Abstract: The successful launch of FengYun-3 has enabled more satellite observations of radiances to be directly assimilated. The introduction of satellite microwave all-sky assimilation technology enhances the utilization of microwave observation data under clear, cloudy, and precipitation conditions. This advancement not only increases assimilated radiances but also improves numerical weather prediction. Consequently, the all-sky approach has received considerable attention recently. In this study, typhoon Maria occurred in July 2018 is studied. In particularly, the all-sky assimilation of FY-3C/MWHS-2 (FengYun-3C/MicroWave Humidity Sounders) data was performed using the Weather Research and Forecasting (WRF) Model based on the three-dimensional variational data assimilation technique implemented in the WRF data assimilation system. The objective was to study the effect of assimilating FY-3C/MWHS-2 data under all-sky conditions and how different types of initial field data affect forecast accuracy in the regional numerical model. Results of clear-sky and all-sky assimilation experiments show that under all-sky conditions, more clouds and precipitation data are assimilated. Improvements were observed in the analysis of the vertical structures (such as the warm core and symmetric wind speed) and humidity fields of typhoon Maria. The average track-error reduction rates ranged from 34% to 62%. These positive effects can be demonstrated in all all-sky experiments utilizing different data types for initializing the WRF model.