Creating one raster with paletted categories from a raster stack

Basically, I’ve stacked a few rasters in R, and I want to create a climate classification map. I have a stack of rasters that have temperature and precipitation information. I want to make one raster map that has distinct climate zones using this data. For example, maybe one zone has an average temperature for more than 24 degrees celsius and an average annual precipitation of less than 250mm, while another one has average temp of 6-12 celsius with more than 500mm of precipitation.

How do I create these one raster with distinct climate categories such as these?