The mass variable of the current 3D-Var regional and global systems remains the geopotential, consequently, the surface pressure is used indirectly as a proximity to surface geopotential datum. Similarly, temperature is not directly assimilated such that significant level temperatures from RAOBS and aircraft temperature reports are not assimilated. Recently, work has been ongoing to introduce the direct assimilation of temperatures and surface pressure from RAOBS instead of geopotentials. Moreover, temperature and moisture from the synoptic meteorological (SM) network are now directly assimilated producing larger and more consistent corrections to the trial field thereby improving the surface and PBL structures. Results from assimilation cycles will be shown to illustrate the impact of surface and upper air temperature data on analyses and 10-day forecasts.