Relationship of cloudiness to near surface temperature over land areas of the Northern Hemisphere for the past several decades is assessed using the data from surface meteorological weather stations, satellite observations, and the NCEP reanalysis project. The overall cloud relationship to near surface temperature is well represented by near surface humidity and surface conditions. Nighttime cloud-related surface warming decreases with the increase in near surface specific humidity. After cloud longwave-related temperature change and snow cover information are removed, one unit of cloud cover is empirically associated with a surface cooling of 0.59 K. The AMIP-1 models generally were able to reproduce the cold season cloud-temperature relationship, but not for the warm season and for the diurnal cycle. The daytime cloud-related surface cooling over China and the contiguous U.S. generally strengthened, but slightly weakened over Canada and the former USSR during the post WWII period. Since the 1970s a prominent increase in atmospheric humidity has weakened cloud longwave effect on surface temperature (best seen at nighttime) over the extratropical land areas. Significant changes and a general redistribution of cloudiness occurred over the contiguous U.S. and the former USSR (south of 60°N) during the past forty to fifty years. Low cloudiness increased over the contiguous U.S. while it decreased over the former USSR (south of 60°N) Total cloud amount and convective cloud frequency increased in both countries.