Looping the 'nearest neighbour' function over rainfall data in each column to handle NaN

1. I have the dataset of rainfall data that has NaN (mm) rainfall values for each date. Rainfall datas are from different stations with Longitude and Latitude.

2. I would like to know how I can loop and fill the NaN values using rainfall value from another nearby rainfall station on the same date.

3. I would then like to keep the final csv product with all the NaNs replaced with 'nearest neighbour' values.

Dataset: https://docs.google.com/spreadsheets/d/1D_k1iB5U-qE2FRRi4MYJ80815YW5FI5jpV0F1uy1ddk/edit#gid=186097297

Thank you so much for your help!