The rainfall and temperature data in the Indian water portal is not exactly the station wise data. The data is interpolated based on the few stations data
it will be better to check your data collected from indian portal with some reported data in research article because as per my personal experience i have found that there can be some false representation of data.
Indeed, before using any dataset we must go through with the metadata. As per discussion, I have also similar view what Mr. Thapa said. In my early days of research(2014-16) I have some question regarding the data set of India water portal 1901-2002 data. I have read all the content and even mail for my understanding. And from this I can said that data set of 1901-2002 is actually based on grided (spatial resolution of 0.5 *0.5 degree) dataset (CRU T2.1) and by the interpolation mean monthly dataset have been prepared (having different citation), and once can go through the metadata. Although, source of some data like district level mean precipitation data for the period of 2004-2008 are from IMD. Hence, I can say that, if you use which ever data set please proper cite the data.
To acknowledge the dataset you may go through the page of http://www.indiawaterportal.org/articles/background-meteorological-datasets. As on this page, all the required information has been given.