I want to obtain the quantity of precipitation for each municipality in Brazil on a given year. For that, I'm trying to use IDW interpolation on QGIS to interpolate the precipitation data from weather stations to municipality centroids. I have two shapefiles, one for the weather stations (with station long-lat and total precipitation data) and another with municipality polygons (from which I obtain the centroids). I'm new to QGIS, but I'm already able to perform an IDW interpolation for the entire map, but cannot find a way designate specific values to the centroids.

If that is possible on QGIS, how do I do it?

  • So do you have the output of your IDW algorithm and you want to assign the value of that to your municipality polygons? – AWGIS Jul 26 at 15:07
  • You can use the "Zonal statistics" tool in the processing toolbox to calculate a number of statistics across each polygon, or, if you want to extract the underlying IDW value to the point you can use the Saga tool "Add raster values to points". – AWGIS Jul 26 at 15:16

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