Terraclimate

http://thredds.northwestknowledge.net:8080/thredds/terraclimate_aggregated.html

Contains freely-available high resolution climate data.

To download the data for the bivariate map of North America, I:

• got a bounding box for North America
  • lat: 6.6/83.3
  • lon: -178.2/-49
• for each datatype of ppt (precipitation), tmax (high temp), tmin (low temp)
  • downloaded the data for that bounding box from this URL:

http://thredds.northwestknowledge.net:8080/thredds/ncss/agg_terraclimate_${datatype}_1958_CurrentYear_GLOBE.nc?var=${datatype}&south=${LAT_MIN}&north=${LAT_MAX}&west=${LON_MIN}&east=${LON_MAX}&disableProjSubset=on&addLatLon=true&horizStride=1&accept=netcdf

Which returns a netcdf file which can be opened by https://www.npmjs.com/package/netcdfjs or similar libraries in other languages.

I haven't found a proper full description of the data set.

That data is aggregate data from 1958-current; you can also get individual years. For example, here is the netCDF file containing the tmin data for 1982:

http://thredds.northwestknowledge.net:8080/thredds/fileServer/TERRACLIMATE_ALL/data/TerraClimate_tmin_1982.nc