Which instrument would be easiest to replace with human observation a hygrometer a rain gauge or a wind vane?

A rain gauge would be the easiest to replace with human observation, as it simply measures the amount of precipitation over a period of time. One can visually assess the depth of collected rainwater and estimate the rainfall amount. In contrast, a hygrometer and wind vane require more precise measurements of humidity and wind direction, respectively, which are harder to accurately gauge without instruments.